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Question (11)

QN0035834

Calcium oxide reacts with water to form calcium hydroxide and releases heat. If the temperature of the reaction mixture rises, the reaction is

(A) endothermic
(B) exothermic
(C) displacement only
(D) photochemical only

Correct Answer: B

Explanation:

A reaction in which heat is released is called an exothermic reaction.

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Question (12)

QN0035835

The reaction C(s) + O₂(g) → CO₂(g) is classified as

(A) decomposition
(B) displacement
(C) combination
(D) double displacement

Correct Answer: C

Explanation:

Two substances combine to form a single product, so it is a combination reaction.

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Question (13)

QN0035836

A reaction has the form AB → A + B. Which type of reaction does this represent?

(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement

Correct Answer: B

Explanation:

A single reactant breaks down into two or more simpler substances, so it is a decomposition reaction.

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Question (14)

QN0035837

Which energy source is involved when silver chloride decomposes in sunlight?

(A) Heat
(B) Electricity
(C) Light
(D) Sound

Correct Answer: C

Explanation:

Silver chloride decomposes in the presence of sunlight, so light supplies the required energy.

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Question (15)

QN0035838

Which gas is produced along with lead oxide when lead nitrate is heated?

(A) SO₂
(B) NO₂
(C) H₂
(D) Cl₂

Correct Answer: B

Explanation:

On heating, lead nitrate decomposes as 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂.

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Question (16)

QN0035839

For the equation 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂, the total number of oxygen atoms on the product side is

(A) 8
(B) 10
(C) 12
(D) 14

Correct Answer: C

Explanation:

2PbO gives 2 oxygen atoms, 4NO₂ gives 8 oxygen atoms and O₂ gives 2 oxygen atoms. Total = 12.

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Question (17)

QN0035840

When 2AgCl decomposes according to 2AgCl → 2Ag + Cl₂, how many molecules of Cl₂ are formed per 2 formula units of AgCl?

(A) 0.5
(B) 1
(C) 2
(D) 4

Correct Answer: B

Explanation:

The coefficient of Cl₂ is 1, so one molecule of Cl₂ is formed from two formula units of AgCl.

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Question (18)

QN0035841

In electrolysis of water, gases are collected at the two electrodes. If one test tube collects twice the volume of the other, the larger volume is

(A) oxygen
(B) hydrogen
(C) nitrogen
(D) chlorine

Correct Answer: B

Explanation:

Water decomposes to hydrogen and oxygen in a 2:1 volume ratio, so hydrogen occupies twice the volume.

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Question (19)

QN0035842

Which reaction is a thermal decomposition reaction?

(A) 2AgCl → 2Ag + Cl₂
(B) CaCO₃ → CaO + CO₂
(C) CaO + H₂O → Ca(OH)₂
(D) Fe + CuSO₄ → FeSO₄ + Cu

Correct Answer: B

Explanation:

CaCO₃ decomposes into CaO and CO₂ on heating. Decomposition caused by heat is thermal decomposition.

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Question (20)

QN0035843

A compound XY decomposes on heating to give X and Y. If 3 units of XY are taken, the maximum number of units of Y formed according to XY → X + Y is

(A) 1
(B) 2
(C) 3
(D) 6

Correct Answer: C

Explanation:

Each unit of XY produces one unit of Y. Therefore, 3 units produce 3 units of Y.

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Question (11)

Calcium oxide reacts with water to form calcium hydroxide and releases heat. If the temperature of the reaction mixture rises, the reaction is

Explanation:

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Question (12)

The reaction C(s) + O₂(g) → CO₂(g) is classified as

Explanation:

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Question (13)

A reaction has the form AB → A + B. Which type of reaction does this represent?

Explanation:

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Question (14)

Which energy source is involved when silver chloride decomposes in sunlight?

Explanation:

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Question (15)

Which gas is produced along with lead oxide when lead nitrate is heated?

Explanation:

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Question (16)

For the equation 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂, the total number of oxygen atoms on the product side is

Explanation:

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Question (17)

When 2AgCl decomposes according to 2AgCl → 2Ag + Cl₂, how many molecules of Cl₂ are formed per 2 formula units of AgCl?

Explanation:

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Question (18)

In electrolysis of water, gases are collected at the two electrodes. If one test tube collects twice the volume of the other, the larger volume is

Explanation:

Link:

Question (19)

Which reaction is a thermal decomposition reaction?

Explanation:

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Question (20)

A compound XY decomposes on heating to give X and Y. If 3 units of XY are taken, the maximum number of units of Y formed according to XY → X + Y is

Explanation:

Link:

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