CBSE Class 12 Chemistry Quiz | CBSE Class 12 Chemistry Short Questions & Answers

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Questions
41 Which of the following statements about the catalyst is true?
A A catalyst accelerates the rate of reaction by bringing down the activation energy.
B A catalyst does not participate in reaction mechanism.
C A catalyst makes the reaction feasible by making ∆G more negative.
D A catalyst makes equilibrium constant more favourable for forward reaction.

Answer: A catalyst accelerates the rate of reaction by bringing down the activation energy.
42 Which among the following is a false statement?
A For a first order reaction,
B Molecularity of a reaction may be zero or fraction.
C Rate of zero order reaction is independent of initial concentration of reactant.
D Half life of a third order reaction is inversely proportional to square of initial concentration of the reactant.

Answer: Molecularity of a reaction may be zero or fraction.
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43 What will be the fraction of molecules having energy equal to or greater than activation energy, Ea?
A e-Ea/Rt
B Ae-Ea/Rt
C A
D K

Answer: e-Ea/Rt
44 The half life of the first order reaction having rate constant K = 1.7 x 10-5s-1 is
A 11.3 h
B 1.8 h
C 12.1 h
D 9.7 h

Answer: 11.3 h
45 For a chemical reaction A→B, it is found that the rate of reaction doubles when the concentration of A is increased four times. The order of reaction is
A Zero
B Half
C Two
D One

Answer: Half
46 Activation energy of a chemical reaction can be determined by __________ .
A determining the rate constant at standard temperature.
B determining the rate constants at two temperatures.
C determining probability of collision.
D using catalyst.

Answer: determining the rate constants at two temperatures.
47 A first order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?
A infinite
B 1.26 × 1015 s
C 2.52 × 1014 s
D 2.52 × 1028 s

Answer: infinite
48 If cone, of reactant ‘A’ is increased 10 times and rate of reaction becomes 100 times. What is order with respect to ‘A’?
A -1
B 1
C 4
D 3

Answer: 1
49 If the initial concentration of reactant is doubled, t1/2 is also doubled, the order of reaction is
A zero
B 3
C 2
D None of these

Answer: zero
50 The rate of first order reaction is 0.04 mol L-1 s-1 at 10 sec. and 0.03 mol L-1 at 2C seconds after initiation of the reaction. t1/2 of reaction is
A 24.1 s
B 34.1 s
C 44.1 s
D 54.1 s

Answer: 24.1 s
51 A first order reaction has specific reaction rate 10-2s-1. How much time it will take for 20g of reactant to reduce to 5g?
A 138.6 s
B 238.6 s
C 346.5 s
D 693.0 s

Answer: 138.6 s
52 Which of the following is affected by catalyst?
A ∆H
B ∆S
C ∆G
D Ea

Answer: Ea
53 The half life period of first order reaction is 1386 seconds. The specific rate constant of the reaction is
A 0.5 × 10-3 s-1
B 5.0 × 10-3 s-1
C 5.0 × 10-2 s-1
D 0.5 × 10-2 s-1

Answer: 0.5 × 10-3 s-1
54 The rate constant of a reaction A → B is 0.6 × 103 mole per second. If the concentration of [A] is 5 M, then what will be concentration of [B] after 20 months?
A 0.72 M
B 3.60 M
C 1.08 M
D 0.36 M

Answer: 0.72 M
55 The rate of first order reaction is 0.04 mol L-1 s-1 at 10 sec. and 0.03 mol L-1 at 2C seconds after initiation of the reaction. t1/2 of reaction is
A 24.1 s
B 34.1 s
C 44.1 s
D 54.1 s

Answer: 24.1 s
56 Which of the following statements about the catalyst is true?
A A catalyst accelerates the rate of reaction by bringing down the activation energy.
B A catalyst makes equilibrium constant more favourable for forward reaction.
C A catalyst does not participate in reaction mechanism.
D A catalyst makes the reaction feasible by making ∆G more negative.

Answer: A catalyst accelerates the rate of reaction by bringing down the activation energy.
57 charcoal at same temperature and pressure is
A CH4 < H2 < SO2
B H2 < CH4 < SO2
C H2 < SO2 < CH4
D SO2 < CH4 < H2

Answer: H2 < CH4 < SO2
58 The formation of micelles takes place only above
A Kraft temperature
B Critical temperature
C Boyle’s temperature
D Inversion temperature

Answer: Kraft temperature
59 Colloidion is 4% solution of which one of the following in alcohol-ether mixture.
A Nitrocellulose
B Glycol dinitrate
C Cellulose acetate
D Nitroglycerin

Answer: Nitrocellulose
60 The protective power of lyophilic colloidal sol is expressed in terms of
A gold number
B oxidation numbers
C CMC (Critical Micelle Concentration)
D coagulation value

Answer: gold number
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