Chemistry · Class X · Chapter-wise Board Questions

AgNO + NaCl → NaNO3 + AgCl (i) (ii) K2SO4 + BaCl2 →>BaSO4 + 2KCl Which of the following options clearly describes both the reactions ? (A)( (i) is double displacement, (ii) is displacement reaction. (B) Both, (i) and (i) are displacement reactions and precipitation reactions. (C) Both, (i) and (i) are double displacement reactions and precipitation reactions. (D) (i) is displacement, (ii) is double displacement reaction.

The gases evolved on heating lead (II) nitrate crystals are : (A) NO and O2 (B) N2 and NO2 (C)NO2 and H2 (D) NO2 and O2

Which of the following are combination reactions ? 1 (i) 2KClO3 ⎯ ⎯→ 2KCl + 3O2 (ii) MgO + H2O ⎯ ⎯→ Mg(OH)2 (iii) 4Al + 3O2 ⎯ ⎯→ 2Al2O3 (iv) Zn + FeSO4 ⎯ ⎯→ ZnSO4 + Fe Options : (A) (i) and (iii) (B) (iii) and (iv) (C) (ii) and (iv) (D) (ii) and (iii)

When ferrous sulphate crystals are heated in a test tube, we observe that : 1 (A) A colourless gas with no smell is evolved. (B) A brown gas is evolved. (C) The green colour of the salt fades and a gas with the smell of burning sulphur is evolved. (D) The green colour of the salt fades and no gas is evolved.

Which of the following is an example of a displacement reaction ? 1 (A) The combustion of natural gas (B) The reaction of a reactive metal with dilute acid (C) The electrolysis of water (D) The reaction of quick lime with water

In the following equation x KI + H2O2 ⎯⎯→ I2 + y KOH x and y respectively are : 1 (A) 2, 2 (B) 1, 2 (C) 2, 1 (D) 1, 1

The volume ratio of hydrogen and oxygen gases liberated during electrolysis of water is 1 (A) 1 : 1 (B) 2 : 1 (C) 4 : 1 (D) 1 : 2

C6H12O6(aq) + 6O2(g) – 6CO2(g) + 6H2O(l). 1 The above reaction is an example of - (A) Displacement Reaction (B) Endothermic Reaction (C) Exothermic Reaction (D) Neutralisation Reaction

The volume ratio of hydrogen and oxygen gases liberated during electrolysis of water is : 1 (A) 1 : 2 (B) 2 : 1 (C) 1 : 3 (D) 4 : 1

In the question two statements are given – one labelled as Assertion (A) and other labelled as Reason (R). Answer this question selecting the appropriate option from (A), (B), (C) and (D) given below : 1 Assertion (A) : Reaction of quick lime with water is an exothermic reaction. Reason (R) : A large amount of heat is evolved on the reaction of quick lime and water. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

On heating ferrous sulphate crystals, one would get : 1 (A) Sweet smell (B) Rotten egg smell (C) Characteristic smell of burning sulphur (D) No smell

Which of the following are exothermic processes ? 1 I. The decomposition of vegetable matter into compost II. Dilution of an acid III. Evaporation of water IV. Sublimation of camphor Options : (A) I and II (B) II and III (C) I and IV (D) III and IV

Assertion (A) : Burning of natural gas is an endothermic reaction. Reason (R) : Methane gas reacts with oxygen to produce CO2 and H2O. 1

Which of the following statements about the given reaction are correct ? MnO, + 4HCl→ MnCl + Cl² + 2H,O (i) MnO, is getting reduced. (ii) HCl is getting oxidised. (iii) MnO, acts as an oxidising agent. (iv) MnO, acts as a reducing agent. (A) (i), (ii) and (ii) (B) (ii) and (iv) (C) (i), (ii) and (iv) (D) (ii) and (iv)

Electrolysis of water is a decomposition reaction. The mass ratio (MH : MO) of hydrogen and oxygen gases liberated at the electrodes during electrolysis of water is : (A) 8 : 1 (B) 2 : 1 (C) 1 : 2 (D) 1 : 8

The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are : (A) Al3O4 and MgO2 (B) Al2O3 and MgO (C) Al3O4 and MgO (D) Al2O3 and MgO2

Assertion (A) : Decomposition reactions are generally endothermic reactions. Reason (R) : Decomposition of organic matter into compost is an exothermic process.

The correct balanced chemical equation showing exothermic reaction in which natural gas burns in air is : (A) CH4 + O2 ⎯ ⎯→ CO2 + 2H2O (B) CH4 + 2O2 ⎯ ⎯→ 2CO2 + 2H2O + Energy (C) CH4 + 2O2 ⎯ ⎯→ CO2 + 2H2O (D) CH4 + 2O2 ⎯ ⎯→ CO2 + 2H2O + Energy

Consider the following chemical equation : p Al + q H2O ⎯ ⎯→ r Al2O3 + s H2 To balance this chemical equation, the values of ‘p’, ‘q’, ‘r’ and ‘s’ must be respectively : 3, 2, 2, 1 (A) (B) 2, 3, 3, 1 2, 3, 1, 3 (C) (D) 3, 1, 2, 2

In which one of the following situations a chemical reaction does not occur? (a) Milk is left open at room temperature during summer (b) Grapes get fermented (c) An iron nail is left exposed to humid atmosphere (d) Melting of glaciers

The main observations while performing the experiment of burning magnesium ribbon in air are : (i) Magnesium ribbon burns with a dazzling white flame. (ii) A white powder is formed. (iii) Magnesium ribbon vapourises. (iv) Aqueous solution of the white powder turns blue litmus to red. (A) (i) and (iv) (B) (ii) and (ii) (C) (i) and (ii) (D) (iii) and (iv)

The values of a, b, c and d in the following balanced chemical equation are respectively : heat, b PbO + c NO, + d O2 a Pb(NO3)2 (A) 1, 1, 2, 1 (B) 1,1,1, 2 (C) 2, 2, 1, 4 (D) 2, 2, 4, 1

Assertion (A) : Silver chloride turns grey in sunlight. Reason (R) : Decomposition of silver chloride into silver and chlorine takes place by sunlight.

In the following experimental setup of electrolysis of water, if P and Q are the gases collected in the test tubes enclosing the electrodes R and S, then select the option/options in which the matching is correct : Test Tube Water Battery (i) P- Oxygen gas R- Anode (ii) P- Hydrogen gas R- Cathode Q - Hydrogen gas S - Cathode (iii) (iv) Q - Oxygen gas S - Anode (A) (i) and (i) (B) (iii) and (iv) (C) (i) and (ii) (D) (ii) and (iv)

Select from the following a statement which is not true about burning of magnesium ribbon in air : (A) It burns with a dazzling white flame. (B) A white powder is formed on burning. (C) It is an endothermic reaction. (D) It is an example of a combination reaction. *31/6/1* [ P.T.O. ]

From the following, select a process in which combination reaction occurs : (A) Black and white photography (B) Burning of carbon (coal) (C) Burning of methane (D) Refining of copper *31/S/1* 3 # [ P.T.O. ]

Select exothermic processes from the following : (i) Dilution of acid (ii) Burning of natural gas (iii) Evaporation of water (iv) Electrolysis of water (A) (i) and (ii) (B) (ii) and (iii) (C) (iii) and (iv) (D) (i) and (iv)

Assertion (A) : Decomposition of vegetable matter into compost is an exothermic reaction. Reason (R) : Decomposition reactions need energy to break down the reactants.

Select from the following a decomposition reaction in which source of energy for decomposition is light : (a) 2FeSO4 →Fe2O3 + SO2 + SO3 (b) 2H20 → 2H2 + O2 (c) 2AgBr → 2Ag + Br2 (d) CaCO3 → CaO + CO2

MnO2 + 4HCl → MnCl2 + 2H2O + Cl2 The reaction given above is a redox reaction because in this case : (a) MnO2 is oxidised and HCl is reduced. (b) HCl is oxidised. (c) MnO2 is reduced. (d) MnO2 is reduced and HCl is oxidised.

Solid Calcium oxide reacts vigorously with water to form Calcium 1. hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction (A) is endothermic and pH of the solution formed is more than 7. (B) is exothermic and pH of the solution formed is 7. (C) is endothermic and pH of the solution formed is 7. (D) is exothermic and pH of the solution formed is more than 7.

Select from the following a process in which a combination reaction is involved : (A) Black and White photography (B) Burning of coal (C) Burning of methane (D) Digestion of food

Identify the correct statement about the following reaction : 2H,S + SO2→ 2H,O + S (A) H,S is oxidising agent and SO, is reducing agent. (B) H,S is reduced to sulphur. (C) SO, is oxidising agent and H,S is reducing agent. (D) SO, is oxidised to sulphur.

Identify the product ‘X' obtained in the following chemical reaction : CaCO. △→'X'+ CO2 (A) Quick lime (B) Gypsum (C) Lime Stone (D) Plaster of Paris

Consider the following Chemical equation : a Al,O, + b HCl→c AIClg + d H,O In order to balance this chemical equation, the values of a, b, c and d must be (A) 1, 6, 2 and 3 (B) 1, 6, 3 and 2 (C) 2, 6, 2 and 3 (D) 2, 6, 3 and 2

Which one of the following reactions is different from the remaining three ? (A) NaCl + AgNO, → AgCl + NaNO CaO + H,O → Ca(OH)2 (B) (C) KNO: + H,SO4 →KHSO4 + HNO: (D) ZnCl, + H,S →ZnS + 2HCl

Zn + 2CH3COOH (CH3COO)2 Zn + H2 The above reaction is a : (A) Decomposition reaction (B) Displacement reaction (C) Double displacement reaction (D) Combination reaction

To balance the following chemical equation, the values of the coefficients x, y and z must be respectively : x Zn(NO3)2 y ZnO + z NO2 + O2 (A) 4, 2, 2 (B) 4, 4, 2 (C) 2, 2, 4 (D) 2, 4, 2

Which of the following is a redox reaction, but not a combination reaction ? (A) C + O2 CO2 (B) 2 H2 + O2 2 H2O (C) 2 Mg + O2 2 MgO (D) Fe2O3 + 3 CO 2 Fe + 3 CO2

In the following case(s) the combination reaction occurs in : I. CuO + H2 II. ZnO + C III. Na + O2 IV. CH4 + O2 (A) Only III (B) Only IV (C) II and III (D) I, III and IV

When aqueous solutions of barium chloride and sodium sulphate react together, an insoluble substance along with aqueous solution of sodium chloride is formed. This reaction is an example of a : (A) combination reaction (B) decomposition reaction (C) displacement reaction (D) double displacement reaction

Select the correct statement from the following about the reaction : CuO + H2 ¾¾® Cu + H2O (A) CuO is getting oxidised and H2 is getting reduced. (B) H2 is getting oxidised and CuO is getting reduced. (C) CuO is a reducing agent. (D) H2 is an oxidising agent.

The emission of brown fumes in the given experimental set-up is due to Brown fumes Lead nitrate Burner (a) thermal decomposition of lead nitrate which produces brown fumes of nitrogen dioxide. (b) thermal decomposition of lead nitrate which produces brown fumes of lead oxide. (c) oxidation of lead nitrate forming lead oxide and nitrogen dioxide. (d) oxidation of lead nitrate forming lead oxide and oxygen.

MnO, + x HCl → MnCl, + y H,O + z Cl, In order to balance the above chemical equation, the values of x, y and z respectively are : (a) 6, 2, 2 (b) 4, 1, 2 (c) 4, 2, 1 (d) 2, 2, 1

Which of the following is an example of endothermic process ? (a) Formation of slaked lime (b) Decomposition of vegetable matter into compost (c) Dissolution of ammonium chloride in water (d) Digestion of food in our body

In order to balance the following chemical equation, the values of the coefficients x and y respectively are : Heat x Pb(NO3)2 2 PbO + y NO2 + O2 (a) 2, 4 (b) 2, 2 (c) 2, 3 (d) 4, 2

When aqueous solutions of potassium iodide and lead nitrate are mixed, an insoluble substance separates out. The chemical equation for the reaction involved is : 1 (a) KI + PbNO3 PbI + KNO3 (b) 2KI + Pb(NO3)2 PbI2 + 2KNO3 (c) KI + Pb(NO3)2 PbI + KNO3 (d) KI + PbNO3 PbI2 + KNO3

A metal ribbon ‘X’ burns in oxygen with a dazzling white flame forming a white ash ‘Y’. The correct description of X, Y and the type of reaction is : 1 (a) X = Ca ; Y = CaO ; Type of reaction = Decomposition (b) X = Mg ; Y = MgO ; Type of reaction = Combination (c) X = Al ; Y = Al2O3 ; Type of reaction = Thermal decomposition (d) X = Zn ; Y = ZnO ; Type of reaction = Endothermic

Assertion (A) : Reaction of Quicklime with water is an exothermic reaction. Reason (R) : Quicklime reacts vigorously with water releasing a large amount of heat. 1

The balanced chemical equation showing reaction between quicklime and water is : (a) 2 CaO + H2O 2 CaOH + H2 + Heat (b) CaO + H2O Ca(OH)2 + H2 + Heat (c) CaO + H2O Ca(OH)2 + Heat (d) 2 CaO + 3 H2O 2 Ca(OH)3 + O2 + Heat

Study the following chemical reaction : 2 Na (s) + 2 H2O (l) 2 NaOH (aq) + H2 (g) The reducing agent in this reaction is : (a) Na (b) H2O (c) NaOH (d) H2

Select the appropriate state symbols of the products given as X and Y in the following chemical equation by choosing the correct option from table given below : W3H + ()tosuZ(osH +()uz (X) (Y) (a) (s) () (b) (aq) (g) (c) (aq) (s) (d) (g) (aq)

Consider the following chemical equation I and II Mg + 2HCl → MgCl² + H2 H. NaOH +HCl → NaCl+ H,O The correct statement about these equations is - (a) I' is a displacement reaction and II' is a decomposition reaction. (b) I' is a displacement reaction and II' is double displacement reaction. (c) Both I' and II' are displacement reactions. (d) Both ‘I' and 'II' are double-displacement reactions.

In the electrolysis of water, if the mass of the gas collected at the anode is ma and the mass of the gas collected at the cathode is mc, the value of (mc/ma) is : (a) 8 (b) 16 1 1 (c) (d) 16 8

Consider the following substances : (i) Acidified K2Cr2O7 (ii) Alkaline KMnO4 (iii) Oxygen (iv) Hydrogen Out of these, the commonly used oxidising agents are : (i) and (ii) only (a) (b) (ii) and (iii) only (c) (i), (ii) and (iii) (d) (i), (ii) and (iv)

Assertion (A) : In the reaction, Na2SO4 + BaCl2 BaSO4 + 2NaCl, sodium chloride is precipitated. Reason (R) : When an aqueous solution is added to another aqueous solution, an insoluble substance is formed, which is called precipitate.

Chameleons contain crystals that reflect light and produce colour. Adjusting the 1 spacing between these crystals, they can alter the wavelengths of light reflected, thus changing their skin colour. Based on the above information, we can infer that the change in colour by chameleons is a: A. chemical change because change in colour takes place. B. chemical change because wavelength of reflected light changes. C. physical change because the space between crystals is adjusted. D. physical change because light is reflected by crystals.

A food label is given below. E304 and E307b are added to the flavoured 1 biscuits. Which of the following is added to food packets for the same reason? A. salt B. vinegar C. nitrogen D. vanilla

Which of the following equations represent redox reactions and what are the 1 values for ‘p’ and ‘q’ in these equations? Equation 1: Fe2O3(s) + 2Al(s) Al2O3 (s) + p Fe(l) + heat Equation 2: 2C4H10(g) + 13O2(g) △ 8CO2(g)+ q H2O(g) A. Only equation 1 is a redox reaction, p =1 and q=3 B. Both equations 1 and 2 are redox reactions, p= 2 and q=4 C. Only equation 2 is a redox reaction, p= 2 and q= 10 D. Both equations 1 and 2 are redox reactions, p= 2 and q=10

In the reaction of aqueous solution of barium chloride with aqueous solution of 1 sodium sulphate, the aqueous solution formed will be: A. BaCl2 B. BaSO4 C. Na2SO4 D. NaCl The following question consists of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. *Please note that the assessment scheme of the Academic Session 2024-25 will continue in the current session C. A is true but R is false. D. A is false but R is true.

for the reaction which takes place. 2

A student performs the following experiment in his school laboratory. List two observations to justify that in this experiment a chemical change has taken place. 2

(a) List the possible sources of energy required in decomposition reactions. Illustrate any one with a suitable example. 2 OR (b) What is observed when hydrated ferrous sulphate crystals are heated in a dry boiling tube ? Give balanced chemical equation(s) of the reactions(s) that occur(s). 2

Define oxidation. Identify and name the substance oxidised in the following reaction : CuO + H2 →Cu + H2O

l. A crystalline substance of green colour ‘X' emits gases of characteristic 21. odour when heated over a flame. It first loses water and changes colour. On further heating, it decomposes and produces a solid compound Y. (a) Identify ‘X' and ‘Y'. (b) State the change in colour observed when 'X' is heated.

Translate the following statements into balanced chemical equations : 2 (a) Aluminium reacts with copper chloride to form aluminium chloride and copper. (b) Zinc reacts with sodium hydroxide to give sodium zincate and hydrogen gas.

Name the type of chemical reaction in which calcium oxide reacts with water. Justify your answer by giving balanced chemical equation for the chemical reaction.

(a) “No precipitation reaction can occur without exchange of ions between the two reactants." Justify this statement giving a balanced chemical equation for the reaction. OR (b) Giving one example of each, differentiate between a displacement reaction and a double displacement reaction.

l. When magnesium ribbon is burnt in air, an ash of white colour is 21. produced. Write chemical equation for the reaction giving the chemical justification for your answer.

(a) Copper powder is taken in a china dish and heated over a burner. Name the product formed and state its colour. Write the chemical equation for the reaction involved. 2 OR (b) Write chemical equation for the chemical reaction which occurs when the aqueous solutions of barium chloride and sodium sulphate react together. Write the symbols of the ions present in the compound precipitated in the reaction. 2

(a) What is observed when aqueous solutions of potassium iodide and lead nitrate are mixed together ? Name the type of reaction and write the chemical equation for the reaction that occurs. 2 OR (b) When copper powder is heated in a watch glass, a black substance is formed. (i) Why is this black substance formed ? Name it. (ii) How can this black substance be reversed to its original form ? 2

l. State whether the given chemical reaction is a redox reaction or not. 21. Justify your answer. MnO, + 4HCl→ MnCl² + 2H,O + Cl²

(a) Name the substance oxidised and reduced in the following reaction : ZnO+ C→ Zn + CO (b) Balance the following chemical reaction : Pb(NO3)2 + KI—> PbI2 + KNO3 Give one example each of electrolytic decomposition and (c) decomposition by sunlight.

Seema took a small amount of copper powder in a china dish and heated it. What changes will she observe on heating ? When H2 gas is passed over this heated substance, what visible changes will be seen in it ? Give the chemical equations of the reactions involved, along with the names and colours of the products in each case. 3

2 g of green coloured crystals of ferrous sulphate are heated in a dry boiling tube. Name the type of chemical reaction taking place. Write the balanced chemical equation for the reaction. Is this an exothermic or an endothermic reaction ? 3

Account for the following : 3 (a) White silver chloride turns grey when exposed to sunlight. (b) Lead (II) nitrate on heating releases brown fumes. (c) Bags of oil and fat containing food items are flushed with nitrogen gas.

What happens when (i) lead (II) nitrate is heated ? (ii) iron (II) sulphate is heated ? (iii) silver chloride is exposed to sunlight ? Write balanced chemical equations of the reactions involved in support of your answer. 31 { }

Beaker Water Hot to touch Quick lime (CaO) (a) Identify the type of reaction taking place and mention why does the beaker become hot. (b) Write the balanced chemical equation. 2+1=3

(a) (i) Define the term decomposition reaction. Write one chemical equation each for decomposition reaction where energy is supplied in the form of heat, light or electricity. (ii) Decomposition of vegetable matter into compost is considered an exothermic reaction. Why ? 3 OR (b) Why are decomposition reactions called the opposite of combination reactions ? Write one chemical equation each for these two types of reactions mentioning the name of the reactant(s) and the product(s) involved in the reactions. 3

(A) Why do we balance a chemical equation? Name and state the law that suggests the balancing of a chemical equation? Balance the following chemical equation : Zn + H3 PO4 → Zn3 (PO4)2 + H2 OR (B) Define a precipitation reaction. Give its example and also express the reaction that occurs in the form of a balanced chemical equation.

Write balanced chemical equation for the reactions that occur when (a) steam is passed over red hot iron. (b) natural gas is burnt in air. (c) glucose reacts with oxygen in the cells of our body and provides energy.

Define a displacement reaction. Name a displacement reaction which is highly exothermic and has its use in joining railway tracks. Explain the process with a balanced chemical equation of the reaction that occurs. 3

Write one chemical equation each for the chemical reaction in which the following have taken place : (i) Change in colour (i) Change in temperature (iii) Formation of precipitate Mention colour change/temperature change (rise/fall)/compound precipitated along with equation.

Study the experimental set-up shown in the diagram and write chemical equation for the chemical reaction involved. Name and define the type of reaction. List two other metals which can be used in place of iron to show the same type of reaction with copper sulphate solution. 3

(a) Write a chemical equation for the reaction in which change in colour is observed when a metal is kept immersed in a salt solution of another metal. (b) When hydrogen gas is passed over heated copper(II) oxide, copper and steam are formed. Write the balanced chemical equation with physical states for this reaction. State what kind of chemical reaction is this. 3

(a) Identify the reducing agent in the following reactions : (i) 4NH, + 50² → 4NO + 6H,0 (ii) H,O + F, →HF + HOF (iii) Fe,O, + 3C0 → 2Fe + 3CO, (iv) 2H, + O, → 2H,0 (b) Define a redox reaction in terms of gain or loss of oxygen.

Silver chloride kept in a china dish turns grey in sunlight. (a) Write the colour of silver chloride when it was kept in the china dish. (b) Name the type of chemical reaction taking place and write the chemical equation for the reaction. (c) State one use of the reaction. Name one more chemical which can be used for the same purpose. 3

(i) While electrolysing water before passing the current some drops of 3 an acid are added. Why ? Name the gases liberated at cathode and anode. Write the relationship between the volume of gas collected at anode and the volume of gas collected at cathode. (ii) What is observed when silver chloride is exposed to sunlight ? Give the type of reaction involved.

(a) Define a double displacement reaction. (b) Write the chemical equation of a double displacement reaction which is also a (i) Neutralization reaction and (ii) Precipitation reaction. Give justification for your answer. 3

With the help of an appropriate example, justify that some of the chemical reactions are determined by (a) Change in temperature, (b) Evolution of a gas, and (c) Change in colour Give chemical equation for the reaction involved in each case.

Amrita electrolysed distilled water using the set-up shown in figure 1. She was 3 expecting two gases to be evolved at the anode and cathode respectively *Please note that the assessment scheme of the Academic Session 2024-25 will continue in the current session Fig.1 Suddenly, she realised that the bulb in the circuit did not glow when she used distilled water (figure 2) Fig. 2 After this realization, she added a substance to the distilled water for electrolysis to take place. Answer the following questions based on the information given above: A. Which gas was she expecting to be formed at the anode and which one at the cathode respectively? B. Why did the bulb not glow when Amrita passed electricity through distilled water? C. Which substance was added by Amrita to distilled water to get the expected result?

Attempt either option (A) or (B) : (A) Write chemical equations for the following when (a) Silver bromide is exposed to sunlight. (b) A piece of lead metal is dropped into copper (II) chloride solution. (c) Hydrogen gas is passed over heated copper oxide. (d) Methane gas is burnt in air. (e) Quick lime is mixed with water. 5×1 OR (B) (a) A pair of tongs Boiling tube -Lead nitrate -Burner Study the experimental setup shown in the diagram and write chemical equation for the same. Name and define the type of reaction. Mention the colour of the products formed. (b) What type of reaction takes place when aqueous solution of lead (II) nitrate and potassium iodide are mixed together ? Write chemical equation also. 3 + 2

(a) What is a chemical reaction ? Describe one activity each to show that a chemical change has occurred in which (i) change of colour, and (ii) change in temperature has taken place. 5 OR (b) (i) Define a decomposition reaction. How can we say that (I) electrolysis of water, and (II) blackening of silver bromide when exposed to sunlight, are decomposition reactions ? Mention the type of energy involved in each case. (ii) The type of reactions in which (I) calcium oxide is formed, and (II) calcium hydroxide is formed are opposite reactions to each other. Justify this statement with the help of chemical equations. 5

Attempt either option A or B. 5 A. I. Refer to the dialogue between Alisha, Drishti and Bhushan in the chemistry lab. They are discussing rusting of iron and formation of ammonia gas. Who all do you agree with and why? Alisha: The formation of ammonia by reaction of nitrogen with hydrogen is a reduction reaction. Dristhti: Both rusting of iron and formation of ammonia are redox reactions. Bhushan: Rusting of iron is an oxidation reaction. II. Assess the following chemical equations. Identify the error(s) and rewrite the equation after correction. (i) MgCl2 + AgNO3 → AgCl2 + MgNO3 (ii) Al + H2SO4 → Al2SO4 + H2O OR B. I. Refer to the dialogue between Daljeet and Avik in the chemistry lab. They have learnt about decomposition reactions. Who has understood decomposition reactions correctly? Justify your answer. Daljeet: During a decomposition reaction, a substance decomposes to give two simpler compounds. MgCO3 decomposes on heating to magnesium oxide and carbon dioxide. Avik: No, during a decomposition reaction, a substance decomposes to give two elements. Water on electrolysis gives hydrogen and oxygen, both are elements. II. Analyse the observations given in following two cases. Are these observations correct? Give reasons to support your answer. (i) Iron fillings are added to an aqueous solution of magnesium sulphate. Observation: The colourless solution turns greenish due to formation of iron sulphate. (ii) Aluminium metal is added to dilute sulphuric acid Observation: Brisk effervescence are seen due to evolution of a gas.

Which one of the following can be used as an acid-base indicator by a visually impaired (blind) student ? (A) Turmeric (B) Vanilla essence (C)Methyl orange (D) Litmus

The natural sources of oxalic acid, lactic acid and methanoic acid respectively are : (A) tomato, curd, ant-sting (B) tomato, orange, nettle-sting (C) orange, milk, ant-sting (D) orange, sour milk, nettle-sting

A metal carbonate reacts with a solution X which forms a salt, water and a gas Y. What are X and Y ? 1 (A) X – Sodium hydroxide, Y – Carbon dioxide (B) X – Sodium hydroxide, Y – Hydrogen (C) X – Hydrochloric acid, Y – Carbon dioxide (D) X – Hydrochloric acid, Y – Hydrogen

The pH of the gastric juices released during digestion is : 1 (A) Less than 7 (B) More than 7 (C) Equal to 7 (D) Equal to 0

Baking powder is a mixture of : 1 (A) Sodium carbonate + Acetic acid Sodium carbonate + Tartaric acid (B) (C) Sodium hydrogen carbonate + Tartaric acid (D) Sodium hydrogen carbonate + Acetic acid

To a small amount of copper oxide in a beaker, when we add dilute hydrochloric acid slowly with stirring, the change in the colour of the solution is due to the formation of : 1 (A) Copper(II) oxide, which is black in colour. (B) Copper(I) chloride, which is blue in colour. (C) Copper(II) chloride, which is blue-green in colour. (D) Copper(I) oxide, which is black in colour.

In which case/cases will the bulb glow considering that all other connections of electric circuit are complete and working ? 1 Case (ii) only (A) Case (i) only (B) (C) Cases (ii) and (iii) (D) Case (iii) only

An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse the change ? 1 (A) Sodium hydroxide (B) Hydrochloric acid (C) Baking soda (D) Slaked lime

How will you protect yourself from the heat generated while diluting a concentrated acid ? 1 (A) By adding acid to water with constant stirring. (B) By adding water to acid with constant stirring. (C) By adding water to acid followed by base. (D) By adding base to acid with constant stirring. { }

Study the following table and select the correct option : 1 Salt Acid used Base used Nature of Salt (A) NaCl HCl NaOH Basic (B) Na2CO3 H2CO3 NaOH Neutral (C) Na2SO4 H2SO4 NaOH Acidic (D) CH3COONa CH3COOH NaOH Basic

Four solutions, namely fructose, ethanol, hydrochloric acid and sodium hydroxide filled in four separate beakers are connected one by one in an electric circuit with a bulb. The solutions in which the bulb will glow when current is passed are : 1 (A) ethanol and hydrochloric acid (B) fructose and ethanol (C) fructose and sodium hydroxide (D) hydrochloric acid and sodium hydroxide

Which of the following statements is true for acids ? 1 (A) Bitter and change red litmus to blue. (B) Sour and change red litmus to blue. (C) Sour and change blue litmus to red. (D) Bitter and change blue litmus to red.

Which of the following salts do not contain water of crystallization ? (i) Bleaching powder (ii) Baking soda (iii) Gypsum (iv) Washing soda (A) (ii) and (iv) (B) (i) and (iii) (C) (ii) and (iii) (D) (i) and (ii)

During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through a guard tube containing calcium chloride. The role of CaCl, taken in guard tube is to - Absorb the evolved gas (A) (B) Moisten the gas (C) Absorb moisture from the gas (D) Absorb chloride ions from the evolved gas

Which of the following acid-base indicators will be used by a visually challenged student to detect the presence of acid in a given solution ? (A) Blue litmus (B) Clove oil (C) Red cabbage extract (D) Methyl orange For question number 24, two statements are given-one labelled as Assertion (A) and the other labelled as Reason (R). Answer this question selecting the appropriate option from (A), (B), (C) and (D) given below : (A)J Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A). Both Assertion (A) and Reason (R) are true, but Reason (R) is not the (B) correct explanation of Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A) : Sodium acetate is a basic salt. Reason (R) : It is because it is a salt of weak acid and strong base.

The following table shows the pH values of four solutions A, B, C and D on a pH scale : B C   3 5 1 2 4 6 7 8 9 10 11 12 13 14   D A The solutions A, B, C and D respectively are of a (A) Strong acid, weak acid, neutral, strong base Weak acid, neutral, weak base, strong base (B) (C) Weak acid, neutral, strong base, weak base (D) Weak acid, neutral, strong base, strong acid

Consider the following reactions : (i) Dilute hydrochloric acid reacts with sodium hydroxide. (ii) Magnesium oxide reacts with dilute hydrochloric acid. (iii) Carbon dioxide reacts with sodium hydroxide. It is found that in each case : (A) Salt and water is formed. (B) Neutral salts are formed. (C) Hydrogen gas is formed. (D) Acidic salts are formed.

The warning sign shown in the given figure must invariably be displayed/pasted on the containers which contain hydroxide of : (A) Aluminium (B) Calcium (C) Sodium (D) Magnesium

The body of human beings works within the pH range of : (A) 61 to 68 (B) 65 to 73 (C) 70 to 78 (D) 75 to 81

Which of the given option represents a family of salts ? NaCl, Na2SO4, CaSO4 (A) (B) K2SO4, Na2SO4, CaSO4 (C) NaNO3, CaCO3, Na2CO3 (D) MgSO4, CuSO4, MgCl2

In order to prepare dry hydrogen chloride gas in humid atmosphere the gas produced is passed through a guard tube (drying tube) which contains : (a) Calcium chloride (b) Calcium oxide (c) Calcium hydroxide (d) Calcium carbonate *31/4/1*

Assertion (A): Concentrated nitric acid is diluted by adding water slowly to acid with constant stirring. Reason (R) : Concentrated nitric acid is easily soluble in water.

A common feature observed in the crystals of washing soda, copper sulphate, gypsum and ferrous sulphate is that all (A) exhibit basic nature (B) exhibit acidic nature (C) have fixed number of molecules of water of crystallisation in one formula unit of these salts. (D) are coloured *31/5/1* [P.T.O. ]

You have three aqueous solutions A, B and C as given below : Potassium nitrate Ammonium chloride Sodium carbonate The ascending order of the pH of these solutions is : (A) Ａ<B<C (B) B<C<Ａ (C) C<A<B (D)B<A<C

Juice of tamarind turns blue litmus to red. It is because of the presence of a chemical compound called (A) Acetic acid (B) Methanoic acid (C) Oxalic acid (D) Tartaric acid

The water of crystallization is present in (i) Bleaching Powder (ii) Plaster of Paris (iii) Washing Soda (iv) Baking Soda (A) (B) (ii) and (iv) (i) and (iii) (C) (i) and (iii) (D) (i) and (iv)

Consider the following compounds : FeSO4 ; CuSO4 ; CaSO4 ; Na2CO3 The compound having maximum number of water of crystallisation in its crystalline form in one molecule is : (a) FeSO4 CuS04 (b) (c) CaS04 (d) Na2CO3

Juice of tamarind turns blue litmus to red. It is because of the presence of an acid called : (A) methanoic acid (B) acetic acid (C) tartaric acid (D) oxalic acid

Select a pair of natural indicator from the following : (A) Litmus and methyl orange (B) Turmeric and Litmus (C) Phenolphthalein and methyl orange (D) Methyl orange and Turmeric

A chemical compound used in glass, soap and paper industries is (A) Washing Soda (B) Baking Soda (C) Bleaching Powder (D) Common Salt

An aqueous solution of a salt turns blue litmus to red. The salt could be the one obtained by the reaction of : (A) HNO3 and NaOH (B) H2SO4 and KOH (C) CH3COOH and NaOH (D) HCl and NH4OH

Four solutions, namely glucose, alcohol, hydrochloric acid and sulphuric acid filled in four separate beakers are connected one by one in an electric circuit with a bulb. The solutions in which the bulb will glow when current is passed are : (A) Glucose and alcohol (B) Alcohol and hydrochloric acid (C) Glucose and sulphuric acid (D) Hydrochloric acid and sulphuric acid

The salt present in tooth enamel is : (A) Calcium phosphate (B) Magnesium phosphate (C) Sodium phosphate (D) Aluminium phosphate

An aqueous solution of sodium chloride is prepared in distilled water. The pH of this solution is : (A) 6 (B) 8 (C) 7 (D) 3

A few drops of turmeric solution are added to a colourless liquid. If the liquid becomes red, the liquid may be : (A) Hydrochloric acid (B) Distilled water (C) Ammonium hydroxide (D) Lemon juice

The acid present in nettle sting is : (A) Acetic acid (B) Methanoic acid (C) Tartaric acid (D) Citric acid

The name of the compound ‘A’ formed in the following reaction is : NaCl + NH3 + H2O + CO2 ¾¾® ‘A’ + NH4Cl (A) Sodium carbonate (B) Ammonium carbonate (C) Sodium hydrogen carbonate (D) Ammonium hydrogen carbonate

In the experimental setup given below, it is observed that on passing the gas produced in the reaction in the solution ‘X' the solution ‘X' first turns milky and then colourless. Dilute Hydrochloric Acid Sodium carbonate The option that justifies the above stated observation is that ‘X' is aqueous calcium hydroxide and (a) it turns milky due to carbon dioxide gas liberated in the reaction and after sometime it becomes colourless due to formation of calcium carbonate. it turns milky due to formation of calcium carbonate and on passing (b) calcium hydrogen carbonate which is soluble in water. (c) it turns milky due to passing of carbon dioxide through it. It turns colourless as on further passing carbon dioxide, sodium hydrogen carbonate is formed which is soluble in water. (d) the carbon dioxide liberated during the reaction turns lime water milky due to formation of calcium hydrogen carbonate and after some time it turns colourless due to formation of calcium carbonate which is soluble in water.

The table below has information regarding pH and the nature (acidic/basic) of four different solutions. Which one of the options in the table is correct ? Option Solution Colour of Approximate Nature of pH paper pH value solution (a) Lemon juice Orange Basic (b) Milk of magnesia Blue 10 Basic (c) Red Gastric juice Acidic (d) Pure water Yellow Neutral

Select washing soda from the following : (a) NaHCO; (b) Na,CO.5H,0 (c) Na,CO..10H,0 (d) NaOH

In the given experimental set-up, if the experiment is carried out separately with each of the following solutions the cases in which the bulb will glow is/are : + Solution (i) Dilute hydrochloric acid (ii) Dilute sulphuric acid (iii) Glucose solution (iv) Alcohol (a) (i) only (b) (ii) only (c) (i) and (ii) (d) (ii), (iii) and (iv)

When Sodium bicarbonate reacts with dilute hydrochloric acid, the gas evolved is : 1 (a) Hydrogen; it gives pop sound with burning match stick. (b) Hydrogen; it turns lime water milky. (c) Carbon dioxide; it turns lime water milky. (d) Carbon dioxide; it blows off a burning match stick with a pop sound.

Acid present in tomato is : 1 (a) Methanoic acid (b) Acetic acid (c) Lactic acid (d) Oxalic acid

Sodium hydroxide is termed an alkali while Ferric hydroxide is not because : 1 (a) Sodium hydroxide is a strong base, while Ferric hydroxide is a weak base. (b) Sodium hydroxide is a base which is soluble in water while Ferric hydroxide is also a base but it is not soluble in water. (c) Sodium hydroxide is a strong base while Ferric hydroxide is a strong acid. (d) Sodium hydroxide and Ferric hydroxide both are strong base but the solubility of Sodium hydroxide in water is comparatively higher than that of Ferric hydroxide.

The name of the salt used to remove permanent hardness of water is : 1 (a) Sodium hydrogen carbonate (NaHCO3) (b) Sodium chloride (NaCl) (c) Sodium carbonate decahydrate (Na2CO3.10H2O) (d) Calcium sulphate hemihydrate (CaSO4. 1 2 H2O)

Select a pair of olfactory indicators from the following : (a) Clove oil and vanilla essence (b) Onion and turmeric (c) Clove oil and litmus solution (d) Vanilla and methyl orange

Fresh milk has a pH of 6. To delay its curdling, a chemical substance is added to it, which is : (a) Sodium carbonate (b) Baking powder (c) Sodium hydroxide (Caustic soda) (d) Baking soda (Sodium hydrogen carbonate)

Hydronium ions are formed by the reaction between : (a) Sodium hydroxide and water (b) Calcium chloride and water (c) Hydrogen chloride gas and water (d) Ethanol and water

Few drops of aqueous solution of ammonium chloride are put on a universal indicator paper. The paper turns pink. Study the following table and choose the correct option. Nature Ammonium chloride is a salt of .... Range of pH (a) acidic weak acid and strong base less than 7 (b) basic weak acid and strong base more than 7 (c) acidic strong acid and weak base less than 7 (d) basic strong acid and strong base

． Two salts ‘X' and ‘Y' are dissolved in water separately. When phenolphthalein is added to these two solutions, the solution ‘X' turns pink and the solution 'Y' does not show any change in colour, therefore ‘X' and 'Y are (X) (Y) (a) Na,CO, NH4CI (b) NaHCO3 Na,SO NH CI (c) (d) NaNO. Na2S04

Assertion (A) : It is advised that while diluting an acid one should add water to acid and not acid to water keeping the solution continuously stirred. Reason (R) : The process of dissolving an acid into water is highly exothermic.

Select from the following compounds which is not a base : (a) Sodium hydroxide (b) Calcium hydroxide (c) Sodium sulphate (d) Zinc oxide

You want to test for hardness of water but hard water is not available in the laboratory. Which of the following compounds may be dissolved in pure water to make it hard ? (i) Hydrogen Carbonate of Sodium (ii) Sulphate of Magnesium (iii) Chloride of Calcium (iv) Carbonate of Sodium (a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (i) and (iv)

Rishita summarizes the chlor-alkali process in the following table. 1 Option Product Formed Use I Hydrogen At cathode Used as a fuel II Chlorine At anode Used to make margarines III Sodium Hydroxide Near cathode To make soap IV Sodium Hydroxide Near anode To make bleaching powder Identify the options that are correctly matched. A. I, II and III B. I and III C. II and IV D. I, II, III and IV

Which of the following salts contain water of crystallisation: 1 (i) Plaster of Paris, (ii) Washing soda, (iii) Baking soda and (iv) Gypsum. A. (i), (ii) and (iii) B. (i), (iii) and (iv) C. (ii), (iii) and (iv) D. (i), (ii) and (iv)

1 Assertion (A): Onion extract loses its smell, when it is added to baking soda solution whereas it retains its smell when added to lemon juice. Reason (R): Onion acts as an olfactory indicator.

Methyl orange is added to dilute hydrochloric acid and to aqueous sodium hydroxide. What is the colour of the methyl orange in each solution? 1 Sample colour in dilute colour in aqueous hydrochloric acid sodium hydroxide A Orange Red B Red Yellow C Red Orange D Yellow Red

Which of the following substances when dissolved in equal volume of water, 1 will have the highest pH value? A. Sulphuric acid B. Acetic acid C. Magnesium hydroxide D. Sodium hydroxide

When excess of carbon dioxide is passed through lime water, the milkiness disappears because 1 A. water soluble calcium carbonate converts to water soluble calcium bicarbonate. B. insoluble calcium carbonate converts to water soluble calcium bicarbonate. C. water soluble calcium carbonate converts to insoluble calcium bicarbonate. D. insoluble calcium carbonate converts to insoluble calcium bicarbonate.

(a) A compound ‘A’ is used in soda-lime fire-extinguisher and decomposes on heating to form compound ‘B’. Compound ‘B’ is used for removing permanent hardness of water. Identify ‘A’ and ‘B’. 1 (b) Write chemical formula of Plaster of Paris. At what temperature gypsum is heated to obtain Plaster of Paris ? 1

Define the following terms : (i) Olfactory indicator (ii) Water of crystallization 1+1

(a) Write the formula of the ions which (i) acids, and (ii) bases generate in water solutions. (b) Dry HCl gas does not change the colour of dry litmus paper. Why ? 2

(a) 1 gram of solid sodium chloride was taken in a clean and dry test tube and concentrated sulphuric acid was added to it. (i) Name the gas evolved in the reaction. (ii) What will be observed when this gas is tested with (I) dry, and (II) wet blue litmus paper ? Write your conclusion about the nature (acidic/basic) of this gas. 2 OR (b) Some metals react with acids to produce salt and hydrogen gas. Illustrate it with an example. How will you test the presence of this gas ? 2

(a) (i) A compound ‘X' which is prepared from gypsum has the property of hardening when mixed with proper quantity of water. Identify 'X' and write its chemical formula. (i) State the difference in chemical composition between baking soda and baking powder. OR (b) Write balanced chemical equation for the reaction that occurs when : (i) blue coloured copper sulphate crystals are heated and (ii) Sodium hydrogen carbonate is heated during cooking.

(A) A student took a small amount of copper oxide in a conical flask and added dilute hydrochloric acid to it with constant stirring. He observed a change in colour of the solution. 2 (i) Write the name of the compound formed and its colour. (ii) Write a balanced chemical equation for the reaction involved. OR (B) The industrial process used for the manufacture of caustic soda involves electrolysis of an aqueous solution of compound ‘X’. In this process, two gases ‘Y’ and ‘Z’ are liberated. ‘Y’ is liberated at cathode and ‘Z’, which is liberated at anode, on treatment with dry slaked lime forms a compound ‘B’. Name X, Y, Z and B. 2

(a) in the right position. (i) Identify X and Y (ii) How can X be reobtained from Y ? 2 OR (b) Two solutions M and N give Red and Blue colour respectively with a universal indicator. (i) In which solution will the hydrogen ion concentration be more ? Justify your answer. (ii) If both M and N solutions are mixed and the resultant mixture is tested with a universal indicator, it turns green. What is the nature of the salt formed ? Justify your answer. 2

(a) Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode. OR (b) Write the preparation of following compounds with balanced chemical equation : (i) Baking soda (i) Bleaching powder (ii) Plaster of Paris

Attempt either (a) or (b) : (a) Give reasons : 3×1=3 (i) For dilution of an acid, acid is added into water and not water into acid. (ii) Dry HCl gas does not turn blue litmus red whereas dilute hydrochloric acid does. (iii) Blue colour of Copper(II) sulphate crystals turns white on heating. OR (b) Write the preparation of the following compounds with balanced chemical equation : 3×1=3 (i) NaOH by chlor-alkali process (ii) Baking Soda (iii) Plaster of Paris

(A) (a) Give the chemical name and formula of Plaster of Paris. 3 (b) Write the chemical equation of its preparation. (c) Give any two uses of it. OR (B) (a) Name the acid present in ant’s sting. (b) Give reason : (i) While diluting an acid, it is recommended that the acid should be added to water. (ii) Baking soda is used as an antacid.

(A) Name the acid present in ant sting and give its chemical formula. Give the common method to get relief from the pain and irritation caused by ant sting. (B) Two solutions ‘X' and ‘Y' have pH values 3.0 and 9.5 respectively. Which of these will turn blue litmus to red and which will turn phenolphthalein from colourless to pink ? 2+ 1

(a) Common salt is an important raw material for various chemicals of daily use. State in brief the method of preparation of (i) Sodium hydroxide, and (ii) Sodium hydrogen carbonate from common salt. Write balanced chemical equations of the reactions that occur. 3 OR (b) Design an experimental set-up to demonstrate that ‘‘Alcohol and glucose contain hydrogen but are not categorised as acids’’. Also give the reason to justify this fact. 3

Write chemical formula of washing soda. How is it obtained from baking soda ? List two uses of washing soda. *31/5/1* 17 [ P.T.O. ]

(a) State the chemical property in each case on which the following uses of baking soda are based upon : (i) as an anti-acids (ii) as a constituent in making baking powder (iii) in soda-acid fire-extinguishers OR (b) Write chemical equations to show what happens when an acid reacts with a (i) metal (ii) base and (ii) carbonate Write the name of the main product formed in each case.

(a) Write the name and chemical formula of a sodium compound which is sometimes added for faster cooking. How is it produced from sodium chloride as one of the raw materials ? Give chemical equation for the reaction involved. (b) The compound mentioned in (a) above is also an ingredient of antacids. Why ? 2+1

(i) The pH of a sample of tomato juice is 4.6. How is this juice likely to be in taste ? Give reason to justify your answer. (ii) How do we differentiate between a strong acid and a weak base in terms of ion-formation in aqueous solutions ? (iii) The acid rain can make the survival of aquatic animals difficult. How ?

Write the common name and the chemical name of the compound CaSO4 . 1 2 H2O. Write the method of its preparation. Give chemical equation for the reaction, when water reacts with CaSO4 . 1 2 H2O. 3

(a) What is meant by the term pH of a solution ? The pH of rain water collected from two cities ‘A’ and ‘B’ was found to be 6·1 and 5·3 respectively. The water of which city is more acidic ? Justify your answer. State with reason what would happen to the aquatic life of a pond in which the rain water of city ‘B’ flows. 3 OR (b) (i) Identify the acid and the base from which the following salts are obtained : (I) Sodium chloride (II) Ammonium sulphate (ii) Write the nature, acidic/basic/neutral, of each of the above mentioned salts, giving reason for your answer. 3

(a) Suggest one remedial measure each to counteract the change in pH in human beings in following cases : (i) Production of too much acid in stomach during indigestion (ii) Stung by a honey bee / nettle leaves (b) Fresh milk has a pH of 6. When it changes into curd will its pH increase or decrease ? Why ?

(i) Suggest a safe procedure of diluting a strong concentrated acid. 3 (ii) Name the salt formed when sulphuric acid is added to sodium hydroxide and write its pH. (iii) Dry HCl gas does not change the colour of dry blue litmus paper. Why ?

(a) Sometimes the pH of our mouth gets lower than 5·5. Why ? (b) (c) Why do copper sulphate crystals turn white on heating ? 3

(a) A substance ‘X' is used as a building material and is insoluble in water. When it reacts with dil. HCl, it produces a gas which turns lime water milky. (i) Write the chemical name and formula of X'. (ii) Write chemical equations for the chemical reactions involved in the above statements. OR (b) A metal ‘M' on reacting with dilute acid liberates a gas 'G'. The same metal also liberates gas ‘G' when reacts with a base. (i) Write the name of gas 'G'. (ii) How will you test the presence of this gas ? (iii) Write chemical equations for the reactions of the metal with (1) an acid and (2) a base.

Give reason for the following : 3 A. A solution of sports electrolyte drink conducts electricity, but coconut oil does not. B. Milkiness disappears when excess of carbon dioxide is passed through lime water. C. An iron bridge near the sea rusts much faster than an iron bridge located in a dry hilly region.

Read the following passage and answer the questions that follow : In the given diagram, when electricity is passed through an aqueous solution of a common salt, a substance ‘Z’ is produced, along with the evolution of gases ‘X’ and ‘Y’. When a burning matchstick is brought near the gas ‘Y’, it burns with a pop sound, whereas ‘X’ is used for disinfecting drinking water. When ‘X’ is passed through slaked lime, an insoluble substance ‘A’ is produced. (a) Write the names of the gases ‘X’ and ‘Y’. 1 (b) Write the balanced chemical equation for the formation of substance ‘Z’. 1 (c) (i) What happens : 2 (I) If a drop of red litmus solution is added to the aqueous solution of substance ‘Z’ ? (II) If CO2 gas is passed through ammoniacal solution of aqueous NaCl ? OR (c) (ii) Identify the substance ‘A’ and write the balanced chemical equation of the reaction which takes place in its preparation. 2

The pH plays an important role in our daily life. Strength of acids and bases depends on the number of H+ ions and OH– ions produced by these respectively. pH scale helps in predicting the strength of acids and bases by measuring hydrogen ion concentration in a solution. Answer the following : (a) What type of indicator is used to predict how strong an acid or base is ? (b) Three solutions A, B and C showed pH as 3, 5 and 7. Which solution has the highest concentration of H+ ions ? (c) What are strong acids and weak acids ? OR (c) (i) Under what condition is rainwater called acid rain ? (ii) In the following acids, identify weak acids : Nitric acid, hydrochloric acid, acetic acid, sulphuric acid, formic acid. 1+1+2 { }

Read the following passage and answer the questions that follow : Salts are formed by reactions of acids and bases. Strong acids react with strong bases to form neutral salts. Weak acids react with strong bases to form basic salts. Acidic salts are formed by strong acids and weak bases. Na2CO3 and NaHCO3 are salts of strong base (NaOH) and weak acid (H2CO3). Bleaching powder is prepared when slaked lime reacts with dry chlorine gas. Crystalline salts are hydrated and lose water on heating. Gypsum on heating at 373 K gives Plaster of Paris. (a) What is the formula of POP (Plaster of Paris) ? What is its chemical name ? 1 (b) Name the compound of sodium which is used for softening hard water. What is its chemical formula ? 1 (c) (i) (I) What is water of crystallization ? (II) Write the preparation of bleaching powder. 2 OR (c) (ii) (I) Name an indicator used by visually impaired children. (II) Give one use of bleaching powder. 2

Seawater contains many salts dissolved in it. Common salt is separated from these salts. Deposits of solid salt are also found in several parts of the world. These large crystals are often brown due to impurities. This is called rock salt and is mined like coal. The common salt is an important raw material for chemicals of daily use. (a) Write balanced chemical equations to show the products formed during electrolysis of brine. 1 (b) List two uses of any one product obtained during electrolysis of brine. 1 (c) (i) A mild non-corrosive basic salt ‘A’, used for faster cooking, is strongly heated to produce a compound ‘B’, that is used for removing permanent hardness of water. Identify A and B and also write the equation for the reaction that occurs when A is heated. 2 OR (c) (ii) Define water of crystallisation. Give two examples of salts that have water of crystallisation. 2

Acid-base indicators can be used to distinguish between an acid and a base. Universal indicator, a mixture of several indicators, shows different colours at different concentrations of acids and bases, thereby indicating their pH on the pH scale of 0 – 14. The pH of a solution is measured by pH paper, which is a paper impregnated with a universal indicator. pH Scale Answer the following questions : (a) Solution P is a strong acid while solution Q is a strong base. On the pH scale, where would you place the solutions P and Q ? 1 (b) A solution has a pH of 7. Name a compound you would use to (i) increase its pH, and (ii) decrease its pH. 1 (c) (i) When the pH of a solution is decreased from 4 to 2, what effect does it produce on its hydronium ion concentration ? State the colour change shown by the pH paper. 2 OR (c) (ii) A person is feeling pain and irritation in the stomach due to indigestion. What could be the pH of the fluid in the stomach ? Write the common name of the medicines people use for remedy. Give the chemical name of ‘‘milk of magnesia’’ often used for this purpose. 2

Common salt is a very important chemical compound for our daily life. It's chemical name is sodium chloride and it is used as a raw material in the manufacture of caustic soda, washing soda, baking soda etc. It is also used in the preservation of pickles, butter, meat etc. (i) Name the acid and the base from which common salt can be obtained. (ii) State the nature (acidic/basic/neutral) of sodium chloride. Give reason for the justification for your answer. (iii) (A) What happens when electric current is passed through an aqueous solution of sodium chloride (called brine)? Name the products obtained along with the corresponding places in the electrolytic cell where each of these products is obtained. OR (ii) (B) How is washing soda obtained from sodium chloride? Give chemical equation of the reactions involved in the process. *31/4/1* 21

Salts play a very important role in our daily life. Sodium chloride which is known as common salt is used almost in every kitchen. Baking soda is also a salt used in faster cooking as well as in baking industry. The family of salts is classified on the basis of cations and anions present in them. (a) Identify the acid and base from which Sodium chloride is formed. (b) Find the cation and the anion present in Calcium sulphate. (c) "Sodium chloride and washing soda both belong to the same family of salts." Justify this statement. OR (c) Define the term pH scale. Name the salt obtained by the reaction of Potassium hydroxide and Sulphuric acid and give the pH value of its aqueous solution.

The teacher while conducting practicals in the laboratory divided the students into three groups and gave them various solutions to find out their pH and classify them into acidic, basic and neutral solutions. Group A Lemon juice, vinegar, colourless aerated drink Group B Tomato juice, coffee, ginger juice Group C Sodium hydroxide, sodium chloride, lime water (a) For the solutions provided, which group is/are likely to have pH value (i) less than 7, and (ii) greater than 7 ? 1 (b) List two ways of determining pH of a solution 1 (c) Explain, why the sour substances such as lemon juice are effective in cleaning the tarnished copper vessels. 2 OR (c) by giving two examples. 2

Sara took 2 mL of dilute NaOH solution in a test tube and added two drops of 4 phenolphthalein solution to it. The solution turned pink in colour. She added dilute H2SO4 to the above solution drop by drop until the solution in the test tube became colourless. 40 drops of dilute H2SO4 were used for the change in *Please note that the assessment scheme of the Academic Session 2024-25 will continue in the current session colour from pink to colourless. When Sara added a drop of NaOH to the solution, the colour changed to back to pink again. Sara now tried the activity with different volumes of NaOH and recorded her observation in the table given below: S. No. Volume of dil. Drops of dil. NaOH taken (mL) H2SO4 used 1 2 20 2 3 30 3 4 40 Answer the following questions based on the above information: A. If Sara used concentrated H2SO4 in place of dilute H2SO4, how many drops will be required for the change in colour to be observed? (a) 40 (b) < 40 (c) >40 Justify your answer. B. Sara measured 20 drops of dil. H2SO4 and found its volume to be 1 mL. If Sara observed a change in colour of NaoH solution by using 3 mL of H2SO4, how many mL of NaOH did she add to the test tube initially? OR Sara takes 10 drops of dilute H2SO4 in the test tube and adds two drops of phenolphthalein solution to it. Then she adds NaOH dropwise. Sara observes a change in colour after adding 20 drops of NaOH. What change in colour would she observe and why? C. Write a balanced chemical equation for the reaction taking place in the above experiment. Which of the following is true and why? The reaction is a (a) neutralisation and double displacement reaction (b) neutralisation and precipitation reaction (c) precipitation and double displacement reaction (d) neutralisation, double displacement as well as precipitation reaction.

(a) Name and state in brief the process used to obtain sodium hydroxide from brine. In this process, along with the main product (i.e., sodium hydroxide), two gases A and B are also produced at the two electrodes. Name A and B specifying the name of their respective electrodes. One of these gases, when reacting with dry calcium hydroxide, produces a compound C which is used as an oxidising agent in many chemical industries as well as to make drinking water free from germs. Name C and write the chemical equation for the reaction in its formation. 3+2 OR (b) When dry crystals of ferrous sulphate were heated in a dry boiling tube, some tiny water droplets were observed in the tube after some time. 5´1=5 (i) State the source of these water droplets. (ii) Write the colour change observed during heating. (iii) Write the balanced chemical equation of the reaction that occurs during heating. (iv) How many water molecules are attached per formula unit of ferrous sulphate crystal ? (v) Write the molecular formula of crystalline form of (I) copper sulphate, and (II) sodium carbonate. *31/S/1* 19 # [ P.T.O. ]

(a) (i) Five solutions A, B, C, D and E when tested with pH paper showed pH as 4, 1, 13, 7 and 10 respectively. Which solution is : (1) Strongly acidic (2) Strongly alkaline (3) Weakly acidic (4) Neutral and (5) Weakly alkaline ? Arrange the solutions in increasing order of H+ ion concentration. (i) Write the name and formula of (1) an acidic salt and (2) a basic salt giving the name of the parent acid and parent base used to form the salt in each case. OR 34. (b) Name and state in brief the process which is used to prepare sodium hydroxide from sodium chloride. In this process along with the main product two gases ‘X' and ‘Y' are also given off at the two electrodes. Name ‘X' and Y' specifying the name of their respective electrode at which each gas is obtained. One of these gases when reacts with dry calcium hydroxide produces a compound ‘Z' which is widely used in water treatment plants and textile industries. Name Z and write chemical equation for the reaction involved in its formation.

(a) A few crystals of ferrous sulphate were taken in a dry boiling tube and heated. Tiny water droplets were observed in the tube after some time. (i) From where did these water droplets appear ? Explain. (ii) What colour change will be observed during heating ? (iii) How many molecules of water are attached per molecule of FeSO4 crystal ? Write the molecular formula of crystalline forms of (I) Copper sulphate, and (II) Sodium carbonate. (iv) State how is Plaster of Paris obtained from gypsum. Write two uses of Plaster of Paris. 5 OR (b) cakes faster cooking. (i) (ii) soft and spongy ? Illustrate the reaction with suitable chemical equation. (iii) Write the name and chemical formula of a mild base other 5

(a) (i) An aqueous solution turns blue litmus red. Which of the following solutions when added in excess would reverse the change ? (1) Lemon juice Magnesium hydroxide (2) Vinegar (3) (4) Calcium sulphate (ii) Out of the following, which compound/compounds will turn the phenolphthalein solution pink ? (1) CH3COOH Ca(OH)2 (2) (3) HCl NaOH (4) (iii) Name a gas whose aqueous solution is basic. Write the formula/name of this solution. (iv) A basic substance is used to treat a honey-bee sting. Why ? (v) Name the acid which is present in (1) Tomato and (2) Tamarind. 5 OR (b) (i) Define water of crystallisation. (ii) Write the chemical name and formula of a compound having water of crystallisation in its molecule and appears blue. (iii) Write the chemical formula of bleaching powder. Write a balanced chemical equation of the reaction involved in its preparation. List its three uses. 5

Which of the following is a poor conductor of electricity ? (A) Pb (B) Cu (C) Ag (D) Al

When an element ‘X' reacts with water, it starts floating. Identify the element ‘X' : (A) Potassium (B) Calcium (C) Sodium (D) Iron Directions : For question number 24, two statements are given, one labelled as Assertion (A) and the other is labelled as Reason (R). Select the correct answer to this question from the codes (A), (B), (C) and (D) as given below : (A) Both, Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both, Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

When Mg metal is treated with hot water, it starts floating on the surface of the water. The reason for its different behaviour is : 1 (A) Mg is a lighter element than water. (B) Mg reacts with water to produce H2 gas which helps in floating. (C) Mg reacts with water to produce N2 gas which helps in floating. (D) Mg reacts with water to form CO2 gas which helps in floating.

A student notices that her silver jewellery turned dull and had a grey-black coating over it after wearing for a few months. What results in the change in colour of the silver metal ? 1 (A) The polish over the jewellery was removed after wearing for a few months. (B) The jewellery comes in contact with air, moisture and acids and corrodes. (C) Dust particles over the jewellery change its colour. (D) Its colour changes due to rusting. For Question number 24, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to this question from the codes (A), (B), (C) and (D) as given below. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

The reaction of calcium with cold water is : 1 (A) Less violent, but the heat evolved is sufficient for the hydrogen to catch fire. (B) Very violent and exothermic and hydrogen catches fire. (C) Exothermic, but the heat evolved is not sufficient for the hydrogen to catch fire. (D) Slow and endothermic.

When zinc reacts with NaOH, the product formed is : 1 (A) Na2O (B) ZnO (C) Na2ZnO2 (D) Zn(OH)2 For Question number 24, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to this question from the codes (A), (B), (C) and (D) as given below. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

Which one of the following metals does not react with cold water ? 1 (A) Sodium (B) Potassium (C) Calcium (D) Magnesium

Alloys are homogeneous mixture of metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents ? 1 (A) Brass (B) Bronze (C) Amalgam (D) Steel

Which of the following is an amphoteric oxide ? 1 (A) Na2O (B) K2O (C) CO2 (D) Al2O3 { }

Which gas is evolved when magnesium metal reacts with very dilute HNO3 ? 1 (A) Oxygen (B) Nitrogen (C) Hydrogen (D) Nitrogen Dioxide { }

Although most of the metals form basic oxides, which of the following metals forms an amphoteric oxide ? 1 (A) Na (B) Ca (C) Al (D) Cu

Reaction between two elements A and B, forms a compound C. A loses electrons and B gains electrons. Which one of the following properties will not be shown by compound C ? (A) It has high melting point. (B) It is highly soluble in water. (C) It has weak electrostatic forces of attraction between its oppositely charged ions. (D) It conducts electricity in its molten state or aqueous solution.

The metals obtained from their molten chlorides by the process of electrolytic reduction are : (A) Gold and silver (B) Calcium and magnesium (C) Aluminium and silver (D) Sodium and iron

The formation of magnesium oxide is correctly shown in option :

Aluminium powder is used in thermit welding because : (A) Its reaction with iron is highly exothermic. (B) When it is heated with iron (III) oxide, molten iron is obtained. (C) When it is heated with iron (III) oxide, molten aluminium oxide is obtained to join railway tracks. (D) Its melting point is low as compared to iron and a molten alloy of iron and aluminium is formed on heating which is used to join railway tracks.

Two metals zinc and tin are dissolved separately in definite proportions in molten copper (the primary metal) to obtain two different alloys respectively known as : (A) Bronze and Brass (B) Brass and Solder (C) Brass and Bronze (D) Solder and Bronze

Assertion (A) : The metals high up in the reactivity series cannot be obtained from their compounds by heating with carbon. Reason (R) : Displacement reactions can also be used to obtain metal.

Assertion (A) : Nichrome is an alloy which is commonly used in electrical heating devices such as electric irons, toasters, etc. Reason (R) : The resistivity of nichrome is high and its resistance decreases with increase in temperature.

The most common method of extraction of metals from their oxide ores is : (A) Reduction with carbon (B) Reduction with hydrogen (C) Reduction with aluminium (D) Electrolytic reduction

Assertion (A) : Hydrogen gas is not evolved when a metal reacts with nitric acid. Reason (R) : Nitric acid is a strong reducing agent and reduces the hydrogen produced in the reaction to water.

The property by virtue of which a solid material can be drawn into thin wires is called : (a) malleability (b) ductility (c) rigidity (d) resistivity

A metal, M, displaces iron from aqueous solution of ferrous sulphate but fails to do so in case of aqueous solution of aluminium sulphate. The metal M is (B) (A) Magnesium Copper Lead Zinc (C) (D)

A metal, X', on treatment with sodium hydroxide liberates a gas ‘G'. It also liberates the same gas, 'G' on treatment with dilute sulphuric acid. Based on above information, ‘X' and ‘G' respectively are (A) Copper and Sulphur dioxide (B) Zinc and Sulphur dioxide (C) Zinc and Hydrogen (D) Copper and Hydrogen

During electrolytic refining of copper, the anode, the cathode and the electrolyte used respectively are (A) Impure copper, pure copper, acidified copper sulphate solution (B) Pure copper, impure copper, sulphuric acid (C) Pure copper, impure copper, acidified copper sulphate solution (D) Impure copper, pure copper, distilled water

The colour of the solution observed after about 1 hour of placing iron nails in copper sulphate solution is (A) Blue (B) Pale green (C) Yellow (D) Reddish brown

The most malleable metals are : (A) Iron and gold (B) Copper and silver (C) Silver and gold (D) Gold and copper

Consider the reactions of dil. hydrochloric acid with the following metals : Aluminium, Copper, Iron, Magnesium and Zinc The correct observation is : (A) Most vigorous reaction with aluminium and no reaction with iron (B) Most vigorous reaction with magnesium and no reaction with iron (C) Most vigorous reaction with magnesium and no reaction with copper (D) Most vigorous reaction with zinc and no reaction with copper

When 2 mL of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as : (a) NaOH + Zn → NaZnO2 + H2O 2NaOH + Zn → Na2ZnO2 + H2 (b) (c) 2NaOH + Zn → NaZnO2 + H2 (d) 2NaOH + Zn → Na2ZnO2 + H2O

A metal and a non-metal that exists in liquid state at the room temperature are respectively : (a) Bromine and Mercury (b) Mercury and Iodine (c) Mercury and Bromine (d) Iodine and Mercury

Oxides of aluminium and zinc are : (a) acidic (b) basic (c) amphoteric (d) neutral

Assertion (A) : Hydrogen gas is not evolved when zinc reacts with nitric acid. Reason (R) : Nitric acid oxidises the hydrogen gas produced to water and itself gets reduced.

The oxide which can react with HCl as well as KOH to give corresponding salt and water is (A) CuO (B) Al,0: (C) Na,0 (D) K,0

Consider the following cases : (a) CaSO4 + Al (b) CuSO, + Ca (c) FeSO4 + Cu (d) ZnSO4 + Mg The cases in which new products will form are - (A) (a) and (b) (B) (b) and (c) (C) (c) and (d) (D) (b) and (d)

Assertion (A) : Different metals have different reactivities with water and dilute acids. Reason (R) : Extraction of a metal from its ore depends on its position in the reactivity series.

Assertion (A) : A piece of Zinc metal gets reddish brown coating when kept in copper sulphate solution for some time. Reason (R) : Copper is more reactive metal than Zinc.

The metals which are found in both free state as well as combined state are : (A) Gold and platinum (B) Platinum and silver (C) Copper and silver (D) Gold and silver

Assertion (A) : The extraction of metals from their sulphide ores cannot take place without roasting of the ore. Reason (R) : Roasting converts sulphide ores directly into metals.

vely are : (A) Mn, MnO2 (B) Al, Al2O3 (C) Fe, Fe2O3 (D) Mg, MgO

A metal 'X' is used in thermite process. When X is burnt in air it gives an amphoteric oxide ‘Y. ‘X' and ‘Y' are respectively : Fe and Fe,O3 Al and Al,O: (a) (b) (c) Fe and FegO4 (d) Al and Al,O4

Assertion (A) : The colour of aqueous solution of copper sulphate turns colourless when a piece of lead is added to it. Reason (R) : Lead is more reactive than copper, and hence displaces copper from its salt solution.

When zinc reacts with sodium hydroxide, the product formed is : (a) Sodium oxide (b) Sodium zincate (c) Zinc hydroxide (d) Zinc oxide

Among the following, the metal with lowest density is : (a) Lithium (b) Lead (c) Magnesium (d) Aluminium

The number of electrons in the outermost shell of the atom of a non-metal can be : (a) 1, 2 or 3 (b) 3, 4 or 5 (c) 5, 6 or 7 (d) 5, 6 or 8

Assertion (A) : Sodium oxide is an amphoteric oxide. Reason (R) : Metal oxides which react with both acids as well as bases are known as amphoteric oxides.

Which of the following statements is true for an amphoteric oxide ? (a) It reacts only with acid and does not form water. (b) It reacts with acid as well as base to form salt and hydrogen gas. (c) It reacts with both acid as well as base to form salt and water. (d) It reacts only with base and does not form water.

Assertion (A) : In the following reaction ZnO + C Zn + CO ZnO undergoes reduction. Reason (R) : Carbon is a reducing agent that reduces ZnO to Zn.

Metal oxides generally react with acids, but few oxides of metal also react with bases. Such metallic oxides are : Mg0 ZnO Al20: IV. Cao (a) I and II (b) I and II (c) II and IV (d) I and IV

Bronze is an alloy of (a) Copper and Zinc (b) Aluminium and Tin (c) Copper, Tin and Zinc (d) Copper and Tin

2 g of yellow sulphur powder is burnt in a china dish and the fumes are collected in a test tube. Water is added in the test tube and the solution is tested separately with blue and red litmus paper. The correct option is : (a) Blue litmus remains blue and red litmus turns blue. (b) Blue litmus turns red and red litmus remains red. (c) Blue litmus turns red and red litmus turns blue. (d) Blue litmus remains blue and red litmus remains red.

Which one of the following metals is malleable and a poor conductor of electricity ? (a) Copper (b) Zinc (c) Lead (d) Silver

Electrical wires made of aluminum 1 A. corrode easily as aluminium is a very reactive metal. B. corrode easily because porous flaky aluminium oxide is formed. C. do not corrode easily as aluminium oxide forms a protective layer. D. do not corrode easily as aluminium is less reactive than metals like sodium, magnesium and zinc. The following question consists of two statements – Assertion (A) and Reason (R). Answer this question by selecting the appropriate option given below: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.

Four statements about the reactions of oxides with dilute hydrochloric acid and 1 aqueous sodium hydroxide are listed. I. Aluminium oxide reacts with both dilute hydrochloric acid and aqueous sodium hydroxide. II. Calcium oxide reacts with dilute hydrochloric acid and aqueous sodium hydroxide. III. Zinc oxide reacts with both dilute hydrochloric acid and aqueous sodium hydroxide. IV. Sulphur dioxide does not react with either dilute hydrochloric acid or aqueous sodium hydroxide. Which statements are correct? A. I and II B. I and III C. II and IV D. III and IV *Please note that the assessment scheme of the Academic Session 2024-25 will continue in the current session

An iron nail is added to each of the two test tubes ‘P’ and ‘Q’ containing 1 aqueous copper (II) sulphate, and aqueous silver nitrate respectively. Which of the following observation is correct? A. In test tube ‘P’ iron nail is coated with a blue coating and in test tube ‘Q’ there is no reaction. B. Iron nail is coated with a brown coating in test tube ‘P’ and silver coating in test tube ‘Q’. C. There is no reaction in either of the test tubes ‘P’ or ‘Q’. D. There is no reaction in test tube ‘P’ but a silver coating on iron nail is seen in test tube ‘Q’.

(a) What are amphoteric oxides ? (b) Categorise the following based on their nature : ZnO, Na2O, CO2

Read the following passage and answer the questions that follow : One student was comparing the reactivity of different metals for his science project. He added iron filings in four test tubes A, B, C and D containing aqueous solutions of ZnSO4, CuSO4, FeSO4 and Al2(SO4)3. (i) In which of the test tubes will he observe the reaction to be the most vigorous and why ? (ii) Write a balanced equation for the reaction involved. 1+1=2

Show the formation of the following ionic compounds by transfer of electrons between the combining atoms : 1+1=2 (i) Sodium oxide (Na2O) (ii) Magnesium chloride (MgCl2) (Given : Atomic number : Na = 11, Mg = 12, O = 8, Cl = 17)

Write chemical equations for the reactions taking place when : 1+1 (i) Manganese dioxide is heated with aluminium powder. (ii) Steam is passed over red hot iron.

(a) In common practice silver is recovered from silver nitrate solution by the use of copper metal. Name the type of reaction that takes place in this process and give the chemical equation of the reaction involved. (b) Name the method used for refining silver. 2

(A) Show the formation of magnesium chloride by electron transfer. Write the name of the cation and anion present in the compound formed. (Atomic Number of Mg = 12, Cl = 17) OR (B) How is zinc extracted from its ore? Name the processes involved in the extraction and write chemical equations for the reactions that occur during these processes.

l. A light green coloured solution of sulphate salt of metal 'P' is taken in a 21. beaker, a rod of another metal “Q' is put in this solution as shown the following figures : After about 1 hour IPSO4 QS04 (Light Green Solution) (Colourless Solution) Identify the metals ‘P' and ‘Q' and write its chemical equation for the reaction that occurs. State the conclusion of this reaction in terms of reactivity series of metals.

(a) (i) What is an alloy ? (ii) Write the composition of solder and the property which makes it suitable for welding electric wires. 2 OR (b) During electrolytic refining of silver : 2 (i) What are the electrodes – cathode and anode made up of ? (ii) What is anode mud ? Why is it called so ?

Define the terms ductility and malleability. Name an element which exhibits both of these properties giving justification for your answer. 2

(a) hot water, b all. Identify the metals A , B , C and D . 2 OR (b) When two compounds namely sodium chloride and calcium chloride are heated directly, one by one on the flame of a burner, they impart different colours to the flame. (i) Name the colour imparted by (1) sodium chloride and (2) calcium chloride. (ii) Are these compounds soluble in organic solvents such as kerosene or petrol ? Justify your answer. 2

The following activity is set-up in the science lab by the teacher. 2 He clamped an aluminium wire on a stand and fixed a pin to the free end of the wire using wax. Then he heated the wire with a burner from the end where the wire is clamped. Students observed the pin fall off. A. If the teacher replaces aluminium wire by silver wire, will the students’ observation change? Justify your answer. B. Will the aluminium wire melt? Give reason for your answer.

Attempt either (a) or (b) : (a) (i) Write one example each of one metal that is so soft that it can be cut with a knife, and one non-metal that is a good conductor of electricity. (ii) Using the electronic configuration, explain how Mg atom combines with oxygen to form magnesium oxide by transfer of electrons. [Atomic number : Mg = 12, O = 8] 1+2=3 OR (b) Give reasons : 3×1=3 (i) Metal sulphides and carbonates should be converted to their metal oxides in the process of extraction of metals. (ii) Aluminium oxide is considered as an amphoteric oxide. (iii) Metals like Na, K, Ca and Mg are never found in their free state in nature.

Attempt either option (A) or (B). (A) (i) Which method will be used to convert each of them to their respective metal oxides ? (a) Carbonate ore (b) Sulphide ore { } (ii) Write a chemical reaction to illustrate the use of aluminium for joining cracked railway tracks. (iii) During extraction of metals, electrolytic refining is used to obtain pure metals. Which material will be used as anode and cathode for the refining of copper metal by this process ? 3 OR (B) (i) Write all the reactions involved in the extraction of Zn from ZnS. (ii) Hydrogen gas is not evolved when most of the metals react with nitric acid. Give reason. 2+1

(a) ‘‘Displacement reactions also play a key role in extracting metals in the middle of the reactivity series.’’ Justify this statement with two examples. (b) Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon ? 3

(a) With the help of an activity, explain the conditions under which iron articles get rusted. 3 OR (b) (i) Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water. (ii) Write a test to identify the gas evolved (if any) during the 3 reaction of these metals with water.

Write the electron-dot structures of (i) sodium, and (ii) oxygen. Using these structures, show the formation of sodium oxide. Mark the anion and cation present in this compound. 3 (At. No. – Sodium = 11 and Oxygen = 8)

(a) What is a reactivity series of elements ? How is it developed ? Arrange the following elements as they are arranged in the reactivity series : Aluminum, Calcium, Copper, Lead (b) Write balanced chemical equation to show the reaction of iron (III) oxide (Fe2O3) with aluminium. 3

Design an activity to show that metals are good conductors of heat and have high melting points.

(A) Observe the following diagram showing an experiment to determine the conditions under which a metal 'M' corrodes. -DryAir Moist Moist -Air -Air >Metal ‘M" >Metal M' >Metal ‘M' Oil Oil List your observations in each of the three cases A, B and C with reason, if the metal ‘M' is generally protected against corrosion by the method of galvanisation. OR (B) (a) Show the formation of Aluminium Nitride (AlN) by the transfer of electrons. [ At. no. of Al = 13; At. no. of N = 7 ] (b) "Ionic compounds are solids and are generally brittle and break into pieces when pressure is applied." Give reason to justify the statement.

It is observed that Calcium on reaction with water floats on its surface Explain why it happens. Also write a balanced chemical equation for the reaction that occurs. What happens when the aqueous solution of the product of this reaction reacts with Carbon dioxide gas ? Write a balanced chemical equation for the reaction.

Draw a labelled diagram to show electrolytic refining of copper. State what happens when electric current is passed through the electrolyte taken in this case.

State reasons for the following : (a) Zinc oxide is an amphoteric oxide. (b) Sodium metal is stored in bottle filled with kerosene oil In the reactions of nitric acid with metals, generally hydrogen gas is (c) not evolved.

(a) State giving reason the reduction process to obtain the following metals from their compounds : (i) Mercury, (ii) Copper and (iii) Sodium OR 28. (b) State giving reason for the change in appearance observed when each of the following metal is exposed to atmospheric air for some time : (i) Silver, (i) Copper and (ii) Iron

Name the ore of mercury and state the form in which it is found in nature. Write the chemical equations along with the condition required for the reactions involved in the extraction of mercury from its ore. 3

With the help of suitable chemical equations, list the two main differences between roasting and calcination. How is metal reduced from the product obtained after roasting/calcination of the ore ? Write the chemical equation for the reaction involved. 3

Attempt either option A or B. 3 A. An element ‘X’ is stored in kerosene, and cannot be extracted from its ore using a reducing agent. ‘X’ forms an ionic compound on reaction with chlorine. (i) Can we store ‘X’ in water? Give reason to support your answer. (ii) Identify element ‘X’. Name the process used and write the equation for extraction of ‘X’ from its ore. OR B. The domes of many building in Europe are made of copper. These domes now appear greenish in colour. (i) Why do the domes appear greenish though copper is orange-red in colour? (ii) In your opinion, should the copper domes be replaced by iron domes to overcome the problem of change of colour of copper domes? (iii) Domes used to be made from thin sheets of metals. Why did the ancient architects use copper to make domes?

Read the following passage and answer the questions given below : Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like - Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals. (a) Why carbonate or sulphide ores are converted to oxides before extraction of metal from it ? (b) Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide. (c) (i) How is copper obtained from its ore (Cu2S) ? Give equations of the reactions. OR (i) (I) Why highly reactive metals cannot be obtained from their (c) oxides by using carbon as a reducing agent ? (II) Why solder, an alloy of lead and tin, is used for welding electrical wires together ?

Read the following passage and answer the questions that follow : An electrochemical process is used for refining metals by selectively dissolving and depositing them through electrolysis. Electrolytic refining is used for metals like Copper, Zinc, Tin, Nickel, Silver and Gold. (a) Define anode mud. 1 (b) In electrolytic refining of copper, name the anode and the cathode. 1 (c) (i) With the help of chemical equations, show the extraction of copper from its ore Cu2S. 2 OR (c) (ii) Draw a neat and labelled diagram showing electrolytic refining of copper. 2

The Statue of Liberty is one of the seven wonders. It is present on Liberty island in New York harbour in U.S.A. It is made up of a metal. Over a period of time, the metal's colour has changed and statue gives greenish look. Answer the following questions based on the above information : (A) What is corrosion ? (B) Why do silver articles turn black after some time ? (C) Copper reacts with moist gas ‘A' present in the air and slowly loses its shiny surface. It turns green. Identify ‘A' and the substance of green coating formed on the surface of copper. OR (C) What is an alloy ? How is an alloy made ? 1+1+2

Many pure metals like copper, iron and gold are very soft and as such are considered unsuitable for certain uses. Metallic objects around us such as cooking utensils, statues, ornaments, guns etc. are actually not made up of pure metals. Instead of pure metals, alloys are used in the design of most of the useful objects. Making alloys enhances the basic properties of a metal which is the primary constituent (metal) of an alloy. (I) How does electrical conductivity and melting point of a metal change when it is converted to its alloy by mixing a small amount of an element in it ? (II) Name an alloy used for welding two wires together in an electric circuit. Write its major constituents. *31/6/1* [ P.T.O. ] (IH) (a) What are alloys ? How is ‘Brass' (an alloy) prepared ? OR (II)(b) What is stainless steel ? How is it prepared ? Write one important property which makes it more useful in making cooking utensils as compared to its primary metal.

The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining. (i) What is the cathode and anode made of in the refining of copper by this process ? (ii) Name the solution used in the above process and write its formula. (ii) (A) How copper gets refined when electric current is passed in the electrolytic cell ? OR solution. What would you observe after about 2 hours if you dip ., ee eas ds e , aeae o ds Give reason for your observations in each case.

Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded. Answer the following questions : (a) When activity was done with dilute hydrochloric acid, then in which one of the test tubes was the rate of formation of bubbles the fastest and the thermometer showed the highest temperature ? 1 (b) Which metal did not react with dilute hydrochloric acid ? Give reason. 1 (c) (i) Why is hydrogen gas not evolved when a metal reacts with dilute nitric acid ? Name the ultimate products formed in the reaction. 2 OR (c) (ii) Name the type of reaction on the basis of which reactivity of metals is decided. You have two metals X and Y. How would you decide which is more reactive than the other ? 2

Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all. (a) What happens when copper is heated in air ? (Give the equation of the reaction involved). (b) Why are some metal oxides categorized as amphoteric ? Give one example. (c) Complete the following equations : (i) Na,0( (s) +H,O() ~→ (s) (ii) Al,O, + 2 NaOH -→> OR (c) On burning Sulphur in oxygen a colourless gas is produced. (i) Write chemical equation for the reaction. (ii) Name the gas formed. (iii) State the nature of the gas. (iv) What will be the action of this on a dry litmus paper ?

The melting points and boiling points of some ionic compounds are given below : 4 Compound Melting Point (K) Boiling Point (K) NaCl 1074 1686 LiCl 887 1600 CaCl2 1045 1900 CaO 2850 3120 MgCl2 981 1685 These compounds are termed ionic because they are formed by the transfer of electrons from a metal to a non-metal. The electron transfer in such compounds is controlled by the electronic configuration of the elements involved. Every element tends to attain a completely filled valence shell of its nearest noble gas or a stable octet. (i) Show the electron transfer in the formation of magnesium chloride. 1 (ii) List two properties of ionic compounds other than their high melting and boiling points. 1 (iii) (A) While forming an ionic compound say sodium chloride how does sodium atom attain its stable configuration ? 2 OR (iii) (B) Give reasons : 2 (i) Why do ionic compounds in the solid state not conduct electricity ? (ii) What happens at the cathode when electricity is passed through an aqueous solution of sodium chloride ?

Metals are required for a variety of purposes. For this we need their extraction from their ores. Ores mined from the earth are usually contaminated with many impurities which must be removed prior to the extraction of metals. The extraction of pure metal involves the following steps : (1) Concentration of ore (2) Extraction of the metal from the concentrated ore (3) Refining of the metal (a) Name an ore of Mercury and state the form in which Mercury is present in it. 1 (b) What happens to zinc carbonate when it is heated strongly in a limited supply of air ? 1 (c) The reaction of a metal A with Fe2O3 is highly exothermic and is used to join railway tracks. (I) Identify the metal A and name the reaction taking place. (II) Write the chemical equation for the reaction of metal A with Fe2O3. 2 OR (c) We cannot use carbon to obtain sodium from sodium oxide. Why ? State the reactions taking place at cathode and anode during electrolytic reduction of sodium chloride. 2

On the basis of reactivity metals are grouped into three categories - (i) Metals of low reactivity (ii) Metals of medium reactivity (ii) Metals of high reactivity Therefore metals are extracted in pure form from their ores on the basis of their chemical properties. the molten ore. Metals of low reactivity are extracted from their sulphide ores, which are converted into their oxides. The oxides of these metals are reduced to metals by simple heating. (a) Name the process of reduction used for a metal that gives vigorous reaction with air and water both. (b) Carbon cannot be used as a reducing agent to obtain aluminium from its oxide ? Why ? (c) Describe briefly the method to obtain mercury from cinnabar. Write the chemical equation for the reactions involved in the process. OR (c) Differentiate between roasting and calcination giving chemical equation for each.

The iron pillar in Qutab Minar complex in Delhi was built 1600 years ago. It is still standing intact and shows no signs of rusting even today. This shows that the ancient metallurgists of India in those times had fully developed metallurgical processes as well as the techniques of protection of different metals. The protection of metals, was done by several processes like coating of a thin film of another metal, alloying etc. (a) Where is iron placed in the reactivity series of metals ? Write the form/forms in which its ores are found in nature. 1 (b) Differentiate between roasting and calcination. 1 (c) Explain any two methods that are employed to prevent rusting/corrosion of metals. 2 OR (c) Why is aluminium used to join railway tracks or the cracked machine parts of iron ? Write a balanced chemical equation for the reaction which occurs. 2

Aavya and Vihan are studying the properties of metals in school. They decide to 4 design and conduct an experiment to test the relative conduction of heat by metals. They use the apparatus (Figure) with rods of five different metals aluminium, silver, copper, iron and zinc attached to a central point. This central point is heated using a burner. The metal rods are of equal length and thickness. They observe that the candles at the end of the rods fall at different times. (Study the graph) A. On the basis of the graph obtained, which metal is the best conductor of heat? B. Gold is a better conductor of heat than aluminium but it is not as good as copper. The time taken for the candle to drop if one of the rods were made of gold would have been: (i) 15 s (ii) 20 s (iii) 35 s (iv) 10 s Attempt either sub-part C or D. C. The length of all the metal rods is increased by 20% without any change in the thickness. Will the time required for the candles to drop be affected? How and why? OR D. Mayank tries the experiment with an apparatus similar to figure (1). He ensures the length of all metal rods is the same. However, the thickness of rods is not the same in his apparatus. Will the inference he draws on the basis of his experiment be correct? Justify your answer.

Attempt either option (A) or (B) : (A) (i) Give reasons for the following : (I) Ionic compound have generally high melting points and boiling points. (II) Solder, an alloy of lead and tin, is used for welding electrical wires. (III) Carbon cannot reduce the oxides of Na or Mg. (ii) The reaction of compound ‘X’ with aluminium is used to join railway tracks : (I) Identify the compound ‘X’. (II) Name the reaction. (III) Write the balanced chemical equation of the reaction of compound ‘X’ with aluminium. 3+2 OR (B) (i) Write the balanced chemical equations when : (I) A mixture of Cu2O and Cu2S is heated. (II) ZnS is heated in the presence of oxygen. (ii) Give reasons for the following : (I) The wires carrying current in homes have a coating of PVC. (II) To make hot water tanks, copper is used and not steel. (iii) Show the formation of ionic compound CaO with electron dot structure. [Atomic number : Ca = 20, O = 8] 2+2+1 { }

Attempt either (a) or (b) : (a) (i) Write the balanced chemical equation involved in the extraction of : (I) Hg from HgS (II) Zn from ZnCO3 (III) Na from NaCl (ii) Why does sodium chloride : (I) not conduct electricity in solid state ? (II) have very high melting point ? 3+2=5 OR (b) During extraction of metals, electrolytic refining is used to obtain pure metals. (i) Which material will be used as cathode and anode for refining of zinc metal by this process ? (ii) Name the electrolyte used in this process. Where do we get pure zinc after passing electric current ? (iii) How does zinc prevent rusting of iron ? Also, name the process. 1+2+2=5

(a) (i) Consider the following metals : K, Ca, Al, Cu, Ag, Fe Select from the above metals, a metal which I. does not react with oxygen even at high temperature. II. reacts with oxygen at ordinary temperature and forms a protective oxide layer which prevents the metal from further oxidation. III. catches fire when kept in the open. IV. does not burn in oxygen but the hot metal is coated with a black coloured oxide layer. (ii) What are amphoteric oxides ? With the help of balanced chemical equations show that aluminium oxide is an amphoteric oxide. (iii) What are alkalis ? Give one example. 5 OR (b) (i) With the help of balanced chemical equations state the process of extracting (I) mercury from its ore called cinnabar, and (II) copper from its sulphide ore. (ii) Silver and copper articles slowly lose their shiny surfaces when exposed to air. Name the compounds formed on (I) silver articles, and (II) copper articles in the form of coating. 5

(a) Write electronic configurations of two elements X (At. no. 12) and Y (At. no. 17). Show the formation of ionic compound when X and Y combine with each other. Write the name and formula of the compound formed. State what would happen if electric current is passed through the aqueous solution of this compound. Name the ion that will reach at (i) cathode, and (ii) anode. 5 OR (b) (i) Write the name of two metals of moderate reactivity. Which one of the two is more reactive ? How can this fact be demonstrated experimentally in a school laboratory ? (ii) Some metals of moderate reactivity are also found in the Earth’s crust in the form of their carbonates. Name the processes involved in the extraction of metal from them, giving chemical equations for the reactions that occur. 5

The formula of functional group for aldehyde is : (A) -COOH (B) -CHO (C) -C- (D) -OH

Assertion (A) : Carbon shares its valence electrons with other atoms of carbon or with atoms of other elements. Reason (R) : The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining the noble gas configuration.

Assertion (A) : Carbon compounds can form chains, branched and ring structures. Reason (R) : Carbon exhibits the property of catenation. 1

Consider the structures ‘X’ and ‘Y’ given below : H H H H H  –     H C – H H H H – C – C – C – C – H and        H – C –– C – – C – H H H H H    H H H ‘X’ ‘Y’ Which of the following statements are correct ? 1 (i) ‘X’ and ‘Y’ are homologues. (ii) ‘X’ and ‘Y’ have the same structural formula, but different molecular formula. (iii) ‘X’ and ‘Y’ have the same molecular formula, but different structural formula. (iv) ‘X’ and ‘Y’ are structural isomers. (A) (i) and (iii) (B) (i) and (iv) (C) (ii) and (iv) (D) (iii) and (iv)

Assertion (A) : There are large number of compounds with many carbon atoms linked to each other. Reason (R) : Carbon-Carbon bond is very strong and stable. 1

While washing dirty clothes by soap, micelles are formed. Select the correct statement about micelles. 1 (A) The hydrophobic tail of the soap molecule is in the interior of the cluster, whereas hydrophilic end is on the surface of the cluster. (B) The hydrophobic tail is on the surface of the cluster, whereas hydrophilic end is in the interior of cluster. (C) Both hydrophobic tail and hydrophilic end are in the interior of the cluster. (D) Both hydrophobic tail and hydrophilic end are on the surface of the cluster. { }

In the question, two statements are given – One labelled as Assertion (A) and other labelled as Reason (R). Write the correct answer selecting the appropriate option from (A), (B), (C) & (D) given below : 1 Assertion (A) : Pure ethanoic acid is also known as glacial acetic acid. Reason (R) : Pure ethanoic acid often freezes during winter due to its low melting point of 290 K. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

Which of the following set of compounds does not belong to same homologous series ? 1 (A) CH4 and C4H10 (B) C2H6 and C3H8 (C) C3H8 and C5H12 (D) C4H8 and C5H12

Which of the following will not undergo addition reaction ? 1 (A) C4H8 (B) C2H2 (C) C3H8 (D) C2H4

Butanal is a four-carbon compound with the functional group : 1 (A) Carboxylic acid (B) Aldehyde (C) Ketone (D) Alcohol

The soap molecule has a : 1 (A) Hydrophilic head and a hydrophobic tail (B) Hydrophobic head and a hydrophilic tail (C) Hydrophilic head and a hydrophilic tail (D) Hydrophobic head and a hydrophobic tail

The property of carbon atoms by virtue of which they form bonds with other carbon atoms is called : 1 (A) Chemical bonding (B) Polymerisation (C) Catenation (D) Carbonisation For Question number 24, two statements are given one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to this question from the codes (A), (B), (C) and (D) as given below. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

How many bonds can one carbon atom form in a compound ? (A) (B) (C) (D)

Identify the unsaturated compounds from the following : (i) Propane (ii) Propene (ii) Propyne (iv) Chloropropane (A) (i) and (ii) (B) (ii) and (iv) (C) (ii) and (iv) (D) (ii) and (iii)

l. In the compound CH- C -CH, which of the following functional group is 21. present ? (A) (B) Aldehyde Alcohol (C) Carboxylic acid (D) Ketone

Given below are the structures of some hydrocarbons. Select the two structures which are related to each other from the given options : H H H H H H H        (i) H – C – C – C = C – H (ii) H – C – C – C – C – H        H H H H H H H H H H    (iii) (iv) C l – C – C – C = C – H    H H H (A) (i) and (iv) (B) (ii) and (iv) (C) (ii) and (iii) (D) (i) and (iii)

Choose the incorrect statement about the common reaction used in hydrogenation of vegetable oils. (A) It is an addition reaction. (B) It takes place in the presence of nickel or palladium catalyst. (C) The product contains only single bonds between carbon atoms. (D) It is an addition reaction which occurs in the presence of an acid catalyst.

Select from the following a hydrocarbon having one C-C bond and one C=C bond : (a) Benzene (b) Cyclohexane (c) Butyne (d) Propyne

If we make carbon skeleton with four carbon atoms, the two different possible skeletons will be (A) C-C-C; C-C-C-C (B) C-C-C-C; (C) C-C-C-C; C-C (D) C-C-C-C; C-C *31/5/1* [P.T.O. ]

A Hydrocarbon which does not belong to the same homologous series of carbon compounds is (A) C4 H1o (B) CeH14 C, H14 (C) (D) C1o H22

Assertion (A) : Carbon and its compounds are our major sources of fuels. Reason (R) : Most of the carbon compounds on burning release a large amount of heat and light.

The number of covalent bond(s) present in a nitrogen molecule is/are : (Atomic number of nitrogen is 7) (A) 1 (B) 3 (C) 5 (D) 7 *31/S/1* 5 # [ P.T.O. ]

Carbon compounds : (i) are good conductors of electricity. (ii) are bad conductors of electricity. (ii) have strong forces of attraction between their molecules. (iv) have weak forces of attraction between their molecules. The correct statements are : (a) (i) and (ii) (ii) and (iii) (b) (c) (ii) and (iv) (d) (i) and (iii)

Consider the following statements about homologous series of carbon compounds : (a) All succeeding members differ by - CH, unit. (b) Melting point and boiling point increases with increasing molecular mass. (c) The difference in molecular masses between two successive members is 16 u. (d) C,H, and C,H4 are NOT the successive members of alkyne series. The correct statements are - (A) (a) and (b) (B) (b) and (c) (C) (a) and (c) (D) (c) and (d)

The structural formula of Cyclohexane is H- 11 (A) H-C C-H (B) H-C C-H (C) (D) 2231/3/1 P.T.0.

Which one of the following hydrocarbons is different from the others ? (A) CH10 (B) C,H14 (C) (D) C,H6

The number of single and double bonds present in a molecule of benzene (C6H6) respectively, are : (A) 6 and 6 (B) 9 and 3 (C) 3 and 9 (D) 3 and 3

Assertion (A) : Some vegetable oils are healthy. Reason (R) : Vegetable oils generally have long unsaturated carbon chains.

A hydrocarbon which contains two C – C single bonds and one C º C triple bond 4. is : (A) Ethyne (B) Propyne (C) Butyne (D) Benzene

Assertion (A) : Soaps do not form lather (foam) with hard water. Reason (R) : Hard water has calcium and magnesium salts dissolved in it which on reacting with soap form scum.

Consider the structures of the three cyclic carbon compounds A, B and C given below and select the correct option from the following : (A) (B) H- -H H- (C) (a) A and C are isomers of hexane and B is benzene. (b) A is an isomer of hexane, B is benzene and C is an isomer of hexene. (c) A is a saturated cyclic hydrocarbon and B and C are unsaturated cyclic hydrocarbons. (d) A is cyclohexane and B and C are the isomers of benzene.

The total number of electrons shared in the formation of an ethyne molecule is : (a) 6 (b) 3 (c) 10 (d) 4

The electron dot structure of chlorine molecule is : 1 (a) (b) (c) (d)

The correct representation of covalent bonding in an oxygen molecule is :

Assertion (A) : Melting point and boiling point of ethanol are lower than that of sodium chloride. Reason (R) : The forces of attraction between the molecules of ionic compoünds are very strong.

Which one of the following properties of Carbon is not responsible for its formation of large number of compounds ? (a) Tetravalency (b) Isomerism (c) Allotropy (d) Catenation

Manjeet wants to wash clothes, but the water available is hard. He compares the 1 action of soap and detergent in hard water, to decide which one to use for washing his clothes. He observes:  Soap forms scum in hard water.  Detergent produces lather easily in hard water. Which of the following inferences is correct? A. Ca²⁺ and Mg²⁺ ions react with soap, forming insoluble compounds, whereas detergents do not form such insoluble salts. B. Soap is acidic, and detergents are basic. C. Soap react with Na+ ions in hard water to form scum while detergents do not react with Na+ ions. D. Detergents form lather easily because they are ionic compounds and react with Ca²⁺ and Mg²⁺ ions while soaps do not react with hard water.

Which of the following pair of compounds are isomers? 1 A. B. C. D.

Assertion (A): C4H8, C4H6 and C4H10 are members of the same homologous 1 series Reason (R): C4H8, C4H6, C3H4, C3H6, C2H4, C2H2 are unsaturated hydrocarbons.

(a) Select from the following the members of same homologous series : H H H H H      (1) H – C – C – C = O (2) H – C – C – C – H      H H H O H H H O H H H H        (3) H – C – C – C – OH (4) H – C – C – C – C = O      H H H H H (b) What happens to (i) the melting point, and (ii) the solubility of compounds as the molecular mass of the compounds in a homologous series increases ? 2

Distinguish between a saturated and an unsaturated hydrocarbon by flame test. List the products of combustion reaction of a saturated hydrocarbon. 2

The melting and boiling points of carbon compounds are generally low and they are largely non-conductors of electricity. State two conclusions based on these two properties. 2

(a) Write the molecular formula of the following carbon compounds : (i) Methane (ii) Propane (b) Carbon compounds have low melting and boiling points. Why ? 2

"Carbon prefers to share its valence electrons with other atoms of carbon or with atoms of other elements rather than gaining or losing the valence electrons in order to attain noble gas configuration." Give reasons to justify this statement.

Draw the electron dot structure of the following : 2 (a) Cyclohexane (b) Butane

Consider the carbon compounds having following molecular formula : (i) C,H (ii) CgHg (ii) CH (iv) CH (v) CH12 State the number of double covalent bonds present in CgH6 (a) (b) Write the formula of first member of the homologous series to which the carbon compound C4H, belongs. (c) Which one of the above compounds forms ring structure of carbon atoms ? (d) Identify, which of the above compounds, is a member of alkane series.

Draw the electron dot structure of the molecules of (a) Oxygen, and (b) Nitrogen. The atomic numbers of oxygen and nitrogen are 8 and 7 respectively. 2

2 Carbon forms millions of compounds whereas silicon, which is just below it in the Periodic Table, forms a few compounds. Explain the reason for the difference in their ability to form compounds.

Attempt either (a) or (b) : (a) 2H6O) reacts with acidified K2Cr2O7 and on oxidation gives an acidic compound presence of concentrated H2SO4 to give a sweet smelling substance 3 OR (b) Give reasons for the following : 3 1=3 (i) Unsaturated hydrocarbons show addition reactions. (ii) Detergents are better cleansing agents than soaps. (iii) Carbon forms only covalent compounds.

Attempt either option (A) or (B) : (A) (i) State any two reasons for carbon forming a large number of compounds. Why does carbon form compounds mainly by covalent bonds ? Identify the compound which contains aldehyde as its (ii) functional group : C,H,OH, C,H,Cl, C,H,CHO, CH,COCH; 2+1 OR (B) An organic compound X' is a constituent of wine. X' on reacting with acidified K,Cr,O- forms another compound ‘Y' with molecular formula C,HyO2. ‘Y’ produces brisk effervescence with sodium carbonate. (i) Identify ‘X' and ‘Y' (ii) Name the gas evolved when ‘Y' reacts with sodium carbonate (iii) Write the chemical equations involved for the chemical 3×1 reactions taking place.

Why is the conversion of ethanol to ethanoic acid an oxidation reaction ? Name the oxidising agent used in this conversion. Write chemical equation for this oxidation reaction. How is this reaction different from the reaction in which ethanol burns in the presence of oxygen ? 3

(a) An organic compound X when reacts with sodium liberates hydrogen. The same compound X when heated at 443 K in the presence of concentrated sulphuric acid gives an unsaturated hydrocarbon. (i) Identify X (ii) Write the chemical equations for the above mentioned reactions and state the role of concentrated sulphuric acid in the second reaction. 3 OR (b) (i) Why are carbon compounds exceptionally stable ? (ii) Differentiate between saturated and unsaturated compounds. Give structures of both the types of compounds having three carbon atoms in their molecules. 3

(a) Draw two different possible structures of a saturated hydrocarbon having four carbon atoms in its molecule. What are these two structures of the hydrocarbon having same molecular formula called ? Write the molecular formula and the common name of this compound. Also write the molecular formula of its alkyne. 3 OR (b) (i) Write the molecular formula of benzene and draw its structure. (ii) Write the number of single and double covalent bonds present in a molecule of benzene. (iii) Which compounds are called alkynes ? 3

Consider the following organic compounds : (i) H- C-C-C=O (ii) H- C- C=O (a) Name the functional group present in their compounds. (b) Write the general formula for the compounds of this functional group. (c) State the relationship between these compounds and draw the structure of any other compound having similar functional group. OR (a) Draw the electron dot structure for ethyne. 1+2 = 3 (b) List two differences between the properties exhibited by covalent compounds and ionic compounds.

(a) State the reason why (i) carbon compounds have low melting and boiling points. (ii) carbon compounds do not conduct electricity. (iii) carbon can form only covalent compounds. 3 OR (b) What is a homologous series ? Find the difference in molecular mass between the two consecutive members of a homologous series. State how in a homologous series of carbon compounds the following properties vary with increase in molecular mass : 3 (i) Melting and boiling points (ii) Chemical properties

l. “Two different forms of carbon - diamond and graphite have different 11. chemical properties are same." Explain why. OR State the reasons, why carbon cannot (i) Lose four electrons to form C4+ cation, and (ii) Gain four electrons to form C4- anion. How does carbon overcome this problem to form compounds ?

(a) (i) In the given below compound H H | | H C C O H | | H H identify (I) the heteroatom, and (II) the functional group. (ii) Write the structural formula of butane (C4H10). (iii) Draw the complete structure of the molecule of (I) Cyclohexane, and (II) Benzene. Which of the two is unsaturated ? 3 OR (b) (i) A compound with molecular formula C3H6O has two isomers. (I) Draw the structures of both the isomers. (II) Write their functional group. (ii) Why are the compounds of carbon exceptionally stable ? 3

Attempt either option A or B. 3 A. An organic compound “X” with formula C2H6O is used to blend with petrol in order to reduce the dependence on fossil fuels and lower down the harmful emissions from the cars. It is also used as a solvent in medicines such as tincture iodine, cough syrups and many tonics. (i) Draw the electron dot structure of “X”. (ii) Write the name and formula of the next homologue of “X”. (iii) Write the reaction of “X” with acetic acid to form a sweet smelling substance. OR B. Ramya performs an experiment in the following two steps: Step 1: Heats ethanol with conc. H₂SO₄ at 170°C to get product A. Step 2: Passes hydrogen gas over product A, using Ni as a catalyst and gets product B. (i) Name the products A and B. (ii) Write the reactions involved in both the steps.

Alcohol forms a homologous series with general formula CnH2n + 1 –OH and –OH group as functional group. Ethanol is commonly called alcohol and is used in alcoholic drinks. It is good solvent, used in medicines, cough syrups, tonics etc. 1+1+2 (a) Write structural formula and name of 4th member of alcohol homologous series. (b) What happens when ethanol is heated with alkaline KMnO4 ? Write chemical equation involved. (c) Write the chemical equation of reaction of ethanol with ethanoic acid in the presence of concentrated H2SO4. Write the name of this reaction. OR (c) What happens when ethanol is heated with excess concentrated sulphuric acid at 443 K ? Write chemical equation involved. What is the role of concentrated sulphuric acid in this reaction ? { }

‘A’ and ‘B’ are two salts used for washing purposes. Salt ‘A’ is used for bathing also. Four test tubes I, II, III and IV as mentioned below are taken. I. Rain water + solution of salt ‘A’ II. Rain water + solution of salt ‘B’ III. Tubewell water + solution of salt ‘A’ IV. Tubewell water + solution of salt ‘B’ The test tubes are shaken one by one almost identically for the same time and the lengths of foam formed in each test tube is noted. (a) In which one of the four test tubes is the foam formed the minimum ? 1 (b) Differentiate between salt A and salt B. 1 (c) (i) What are esters ? What happens when an ester reacts with an alkali (say sodium hydroxide) ? Give chemical equation for the reaction. 2 OR (c) (ii) What is the cause of hardness of water ? Sometimes it is observed that while bathing foam is formed with difficulty and an insoluble substance is formed. Name this substance and write the cause of its formation. 2

The combining capacity of various elements depends on the number of valence electrons. Also the reactivity of elements is explained as their tendency to attain a completely filled outer shell, that is, to attain a noble gas configuration. This may be either through gain of electrons or loss of electrons or sharing of electrons. (a) An element A has atomic number 16, how will it attain its nearest noble gas configuration ? (b) Write the number of (i) single and (i) double covalent bonds in a molecule of butene (C4Hg). (c) (A) Explain the formation of a molecule of ammonia (NHg), using electron dot structure. (Atomic number of nitrogen is 7) OR (B) Why does carbon share its valence electrons with other atoms of (c) carbon or with atoms of other elements ? *31/5/1* [ P.T.O. ]

All compounds of carbon which contain only carbon and hydrogen are called hydrocarbons. Among these, saturated hydrocarbons are called ‘alkanes’, unsaturated compounds with one or more double bonds are called ‘alkenes’ and compounds containing one or more triple bonds are called ‘alkynes’. (a) Identify the following compound and write its name. 1 CH3 − C  CH (b) How do saturated and unsaturated carbon compounds differ in terms of the flame produced by them on burning ? 1 (c) (i) Which type of hydrocarbons undergo addition reactions ? Show with an example. 2 OR (c) (ii) What are structural isomers ? Draw two structural isomers of butane (C4H10). 2 *31/S/1* 23 # [ P.T.O. ]

More than three million carbon compounds have been discovered in the field of chemistry. The diversity of these compounds is due to the capacity of carbon atoms for bonding with one another as well as with other atoms. Most of the carbon compounds are poor conductors of electricity and have low melting and boiling points. (a) Write the molecular formula of first two members of homologous series having functional group -Br. (b) Given below are the formulae of some functional groups : -C- (i) (ii) Write the name of these functional groups. What would be observed on adding a 5% alkaline potassium (c) permanganate drop by drop to some warm ethanol taken in a test tube ? State the role of KMnO4 in the reaction and write the chemical equation for the reaction involved. OR (c) Write the name of the compound formed when ethanol is heated at 443 K temperature with excess of conc. H,SO4. What is the role of conc. H,SO4 in the reaction ? Write the chemical equation for the reaction involved.

Carbon is a versatile element that forms the basis of all living organisms and many of the things we use. A large variety of compounds is formed because of its tetravalency. Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements. Answer the following questions : (a) What are hydrocarbons ? 1 (b) List two properties by virtue of which carbon can form a large number of compounds. 1 (c) (i) Write the formula of the functional group present in (1) aldehydes, and (2) ketones. Write chemical equation for the reaction that occurs between ethanoic acid and ethanol in the presence of a catalyst. 2 OR (c) (ii) What are structural isomers ? Write the structures of two isomers of butane (C4H10). 2

Ethanol (commonly known as alcohol) is an important carbon compound widely used in industries, hospitals, etc. Because it is a very good solvent, it is used in medicines such as cough syrups, tincture iodine and many tonics. As it is a cleaner fuel, ethanol is used as an additive in petrol in most of the developed countries of the world. (a) Write the structure of ethanol. 1 (b) Name the products formed when ethanol burns in sufficient air (oxygen). 1 (c) (i) State what happens when 5% solution of alkaline potassium permanganate is added to warm ethanol. Draw the structure of the product formed and state the role of 5% solution of alkaline potassium permanganate in the reaction. 2 OR (c) (ii) State what happens when ethanol is heated with excess conc. H2SO4 at 443 K. Draw the structure of the product formed and state the role of conc. H2SO4 in the reaction. 2

(a) (i) Give reasons for the following : () Covalent compounds are poor conductor of electricity. (II) Soap does not form lather in hard water. (III) Carbon shows catenation but silicon does not. (i) Write chemical equations for the following : () Oxidation of ethanol by acidified K2Cr2O7. (II) Hydrogenation of ethene. OR (b) Mohan heated ethanol with a compound ‘X' in the presence of a few drops of conc. H2SO4 and observed a sweet smelling compound 'Y' is formed. When 'Y' is treated with sodium hydroxide it gives back ethanol and a compound 'Z'. () Identify 'X', 'Y' and 'Z'. (i) Write the role of conc. H2SO4 in the reaction. (ii) Write the chemical equations involved and name the reactions.

Attempt either (a) or (b) : (a) A carbon compound ‘P’ of molecular formula C2H6O is found to be neutral when tested with red and blue litmus. A gas that burns with a pop sound is produced when sodium metal reacts with compound ‘P’. (i) Identify the compound ‘P’. (ii) The carbon compound ‘P’ is heated with conc. H2SO4 at 443 K to produce compound ‘Q’. (I) Write the chemical equation for the reaction. (II) What is the role of conc. H2SO4 in this reaction ? (iii) What is likely to be observed on heating compound ‘P’ with ethanoic acid with an acid as a catalyst ? Write the chemical equation for the reaction. 1+2+2=5 OR (b) (i) Write the structural formula of benzene. (ii) State the reason why carbon can neither form C4+ cation nor C4– anion. (iii) What type of bond is formed between carbon and hydrogen ? (iv) How is ethanol converted to ethanoic acid ? (v) Complete the following chemical equation : 5×1=5 CH3COOC2H5 + NaOH ⎯⎯→

Attempt either (a) or (b) : (a) (i) What is homologous series ? Which two of the following organic compounds belong to the same homologous series ? C2H4, C4H10, C3H4, C4H8 (ii) Write the product(s) in the following reactions : Acid (I) CH3 – CH2 – OH + CH3COOH ⎯⎯⎯⎯→ Burning (II) C2H5OH + O2 ⎯⎯⎯⎯→ (iii) Why does micelle formation take place when soap is added to water ? 2+2+1=5 OR (b) (i) Name the following compounds : (I) CH – C – CH 3 3  O H  (II) H – C – C C – H   H (ii) Name the reaction which is commonly used in the conversion of vegetable oils to fats. (iii) Why is the melting point of C4H10 higher than C3H8 ? (iv) What happens when a piece of sodium is dropped into ethanol ? (v) Write the products in the following reaction : 5×1=5 CH3COOC2H5 + NaOH ⎯⎯→

Attempt either option (A) or (B) : (A) (i) Carbon cannot form C4+ cation and C4– anion. Explain. (ii) Define homologous series of carbon compounds. Why are the melting and boiling points of C4H10 higher than C3H8 or C2H6 ? (iii) What happens when ethanol is heated with acidified potassium dichromate ? 2+2+1 OR (B) (i) How would you name the following : I. CH3 – CH2 – C == O | H II. CH3 – C  CH (ii) When ethanol reacts with ethanoic acid in the presence of conc. H2SO4, a substance with sweet smell is produced. Answer the following : I. State the class of compounds to which the sweet smelling compounds belong. II. Write the chemical equation for the reaction. (iii) Why soaps do not produce foam with hard water ? 2+2+1 { }

(a) (i) Draw two isomeric structures of Butene (C4H8). (ii) Name the following compounds : H H H    (I) H – C – C – C – C l    H H H H H H    (II) H – C – C – C – C – H     H H O H (iii) Write the chemical equations for the following reactions. Mention one essential condition each for these reactions to take place. (I) Ethanol undergoes complete oxidation (II) Propene undergoes hydrogenation (III) Ethanoic acid reacts with ethanol 5 OR (b) (i) A carbon compound X is a good solvent. On reaction with sodium, X forms two products Y and Z. Z is used to convert vegetable oil into vegetable ghee. Identify and name X, Y and Z. Also write the equation of reaction of X with sodium to justify your answer. (ii) Write chemical equation to show what happens when ethanol : (I) burns in oxygen/air. (II) is heated at 443 K in excess conc. H2SO4. (III) reacts with acidified potassium dichromate. 5

(a) (i) A compound ‘X’ having two carbon atoms in its molecule turns blue litmus red and 5 – 8% solution of ‘X’ in water is widely used as a preservative. Identify the compound ‘X’ and 1 1 write its structure. 2 1 (ii) Compare its pH nature with a mineral acid. 2 (iii) ‘X’ on reacting with alcohols produces sweet smelling compounds, used in making perfumes. Name the reaction 1 1 and write its chemical equation. 2 (iv) When sodium carbonate is added to ‘X’, a colourless gas is produced which turns lime water milky. Write the chemical equation for the reaction giving the name of the 1 1 salt produced. 2 OR (b) (i) Differentiate between saturated and unsaturated hydrocarbons by giving one example each, with a structural formula. (ii) Write the method of converting an unsaturated hydrocarbon into a saturated hydrocarbon. Name the industry where this reaction is commonly used. (iii) Write the name and structure of a hydrocarbon having double bond and four carbon atoms in its one molecule. 5

(A) A carbon compound 'A' on heating with excess conc. H2SO4 forms a compound 'B', which on addition of one mole of hydrogen gas in the presence of nickel catalyst forms a compound ‘C'. ‘C' on combustion in air forms 2 moles of carbon dioxide and 3 moles of water. Identify ‘A', ‘B' and ‘C' and write their structures. Give chemical equations of the reactions involved. Also state the role of concentrated sulphuric acid in the formation of 'B' from ‘A'. OR (B) A carbon compound ‘A' is widely used as a preservative in pickles and has a molecular formula C2H4O2. This compound reacts with ethanol to form a sweet smelling compound 'B'. (i) Identify the compound A' and write its structure. (ii) Write the chemical equation for the reaction of A' with ethanol to form compound 'B'. State the role of presence of an acid in the reaction. (ii) How can we get compound ‘A' back from ‘B' ? (iv) How can ‘A' be obtained from ethanol ? (v) Name the gas produced when compound ‘A' reacts with washing soda.

(A) (a) What is meant by the term homologous series of carbon compounds ? Write molecular formula of any two consecutive members of homologous series of ketones. (b) Write chemical equation of the reactions of ethanoic acid with (i) Sodium hydroxide and (i) Ethanol (in the presence of an acid); giving the name of the products in each case. (c) Draw the structure of the molecule of benzene. OR *31/5/1* 21 [ P.T.O. ] (B) (a) Write the molecular formula of ethyne and draw its electron dot structure. (b) Write chemical equation to show the reaction of ethanol with (i) Sodium metal (ii) Ethanoic acid (in the presence of an acid) (ii) Acidified potassium dichromate Write the name of the product formed in each case.

(a) Name an alcohol and a carboxylic acid having two carbon atoms in their structures. Draw their structures and state how this alcohol can be converted into a carboxylic acid. What happens when these two compounds react in the presence of an acid ? Write chemical above. OR (b) What are soaps ? Write the structure of a soap molecule. Explain the cleansing action of a soap. Why are soaps not considered suitable for washing clothes in a region where water is hard ? How is this problem overcomed ?

(A) (i) Define a homologous series of carbon compounds. (i) Why is the melting and boiling points of CaHg higher than that of C3H6 or C2H4 ? homologous series compounds ? (iv) Write the name and structures of (i) aldehyde and (i) ketone with molecular form C3H,O. OR (B) (i) Write the name and structure of an organic compound ‘X' having two carbon atoms in its molecule and its name is suffixed with ‘-ol'. (ii) What happens when ‘X' is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation for the reaction stating the conditions for the reaction. Also state the role played by concentrated sulphuric acid in the reaction. (iii) Name and draw the electron dot structure of hydrocarbon produced in the above reaction.

Give reason why carbon can neither form C4+ cations nor C4- 34. (a) (i) anions but form covalent compounds. (ii) What is homologous series of carbon compound ? Write the molecular formula of any two consecutive members of homologous series of aldehydes. (ii) Draw the structure of the molecule of cyclohexane (C,Hi2). OR (b) (i) Name a commercially important carbon compound having 34. functional group -OH and write its molecular formula. (ii) Write chemical equation to show its reaction with (1) Sodium metal (2) Excess conc. sulphuric acid (3) Ethanoic acid in the presence of an acid catalyst (4) Acidified potassium dichromate Also write the name of the product formed in each case.

(a) A saturated organic compound ‘A' belongs to the homologous series of alcohols. On heating 'A' with concentrated sulphuric acid at 443 K, it forms an unsaturated compound B' with molecular mass 28 u. The compound ‘B' on addition of one mole of hydrogen in the presence of Nickel, changes to a saturated hydrocarbon 'C'. (i) Identify A, B and C. (ii) Write thechemical equations showing the conversion of A into B. (iii) What happens when compound C undergoes combustion ? (iv) State one industrial application of hydrogenation reaction. (v) Name the products formed when compound A reacts with sodium. OR (b) (i) With the help of diagram, show the formation of micelles, when soap is applied on oily dirt. (ii) Take two test tubes X and Y with 10 mL of hard water in each. In test tube ‘X', add few drops of soap solution and in test tube Y' add a few drops of detergent solution. Shake both the test tubes for the same period. (1) In which test tube the formation of foam will be more ? Why? (2) In which test tube is a curdy solid formed ? Why ?

(a) he presence ium ethanoate. Write the chemical equation for the reaction involved and name it, giving justification for the name. 5 OR (b) (i) Name the simplest saturated hydrocarbon. Draw its electron dot structure. Which type of bonds exist in this compound ? (ii) Name any two mixtures of the carbon compound used as a fuel in daily life, of which the above mentioned compound is an important component. (iii) In which homologous series of carbon compounds can this compound be placed ? Write the general formula of the series. (iv) Which type of flame is produced on burning it ? 5

(A) (i) Draw the structure of the following compounds : 5 (a) Butanoic acid (b) Chloropentane (ii) How are structure (i) and structure (ii) given below related to one another ? Give reason to justify your answer. Draw one more possible structure for above case. (iii) Differentiate between saturated and unsaturated carbon compounds on the basis of their general formula. OR (B) (i) What happens when a small piece of sodium is dropped in 5 ethanol ? Write the equation for this reaction. (ii) Why is glacial acetic acid called so ? (iii) What happens when ethanol is heated at 443 K in the presence of conc. H2SO4 ? Write the role of conc. H2SO4 in this case. (iv) Write an equation showing saponification.

(a) 2H6O) on reacting with acidified K2Cr2O7 presence of conc. H2SO4 to give a sweet smelling compoun (i) Identify X , Y and Z (ii) Write the chemical equations for the reactions in the conversion of (1) X to Y and (2) X to Z . (iii) State the role of (1) acidified K2Cr2O7 in the conversion of X to Y and (2) conc. H2SO4 in the reaction of X and Y . (iv) Name the reaction which occurs when Z reacts with an alkali. 5 OR (b) Carry out the following conversions, stating the condition(s) for each : 5 (i) Ethanol Ethene (ii) Ethene Ethane (iii) Ethane Chloroethane (iv) Ethanol Ethanoic acid (v) Ethanoic acid Ethyl ethanoate

A compound ‘A' with a molecular formula of C,H,O, reacts with 34. (a) (i) the name of the functional group it possesses. Write chemical equation for the reaction involved. (ii) When the above stated compound ‘A' reacts with another compound ‘B' having molecular formula C,H.O in the presence of an acid, a sweet smelling compound 'C' is formed. (1) Identify ‘B' and ‘C' (2) State the role of acid in this reaction. (3) Write chemical equation for the reaction involved OR (b) (i) Name the compound formed when ethanol is heated at 443 K in the presence of conc.H,SO4 and draw its electron dot structure. State the role of conc.H,SO4 in this reaction. (ii) What is hydrogenation ? Explain it with the help of a chemical equation. State the role of this reaction in industry.

Attempt either option A or B. 5 A. A hydrocarbon with the formula CxHy undergoes complete combustion as shown in the following equation: 2CxHy + 9O2 → 6CO2 + 6H2O. (a) What are the values of ‘x’ and ‘y’? (b) Give the chemical (IUPAC) name of the hydrocarbon. (c) Draw its electron dot structure. (d) Name the alcohol which on heating with conc. H2SO4 will produce the above hydrocarbon CxHy. *Please note that the assessment scheme of the Academic Session 2024-25 will continue in the current session (e) Write a balanced chemical equation for the reaction of CxHy with hydrogen gas in presence of Nickel. OR B. The electronic structures of atoms P and Q are shown below Based on the information given above, answer the following questions: (a) If P and Q combine to form a compound, what type of bond is formed between them? (b) Give the chemical formula of the compound formed. (c) The compound so formed is dissolved in water. Is the resultant solution acidic or basic in nature? Justify your answer. (d) Write the chemical equation for the reaction between ‘Q’ and ethanol. (e) What will be the formula of the compound formed when ‘P’ undergoes bonding with carbon?