MCQ on Chemical Kinetics for NEET | Chemical Kinetics MCQs

(1) For a first order reaction A → B the rate constant is x min−1 . If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.

[A] 0.01 e^−x

[B] 1 x10^-2 (1-e^-60x)

[C] (1x10^-2) e^-60x

[D] none of these

Answer: (1x10^-2) e^-60x

(2) A zero order reaction X →Product , with an initial concentration 0.02M has a half life of 10 min. if one starts with concentration 0.04M, then the half life is

[A] 10 s

[B] 5 min

[C] 20 min

[D] cannot be predicted using the given information

Answer: 20 min

(3) For a first order reaction A → product with initial concentration x mol L−1 , has a half life period of 2.5 hours . For the same reaction with initial concentration (x/2) mol L−1 the half life is

[A] (2.5 × 2) hours

[B] (2.5 / 2) hours

[C] 2.5 hours

[D] Without knowing the rate constant, t1/2 cannot be determined from the given data

Answer: Without knowing the rate constant, t1/2 cannot be determined from the given data

(4) For the reaction, 2NH3 → N2 + 3H2

then the relation between k1, k2 and k3 is

[A] k₁ = k₂ = k₃

[B] k₁ = 3k₂ = 2k₃

[C] 1.5 k₁ = 3 k₂ = k₃

[D] 2 k₁ = k₂ = 3 k₃

Answer: 1.5 k₁ = 3 k₂ = k₃

(5) The decomposition of phosphine (PH3) on tungsten at low pressure is a first order reaction. It is because the

[A] rate is proportional to the surface coverage

[B] rate is inversely proportional to the surface coverage

[C] rate is independent of the surface coverage

[D] rate of decomposition is slow

Answer: rate is independent of the surface coverage

(6) For a reaction Rate = k[acetone]3/2 acetone then unit of rate constant and rate of reaction respectively is

[A] (mol L^-1s^-1), (mol^-1/2 L^1/2 s^-1)

[B] (mol^-1/2 L^1/2s^-1), (mol L^-1 s^-1)

[C] (mol^1/2 L^1/2s^-1), (mol L^-1 s^-1)

[D]

(mol Ls^-1), (mol^1/2 L^1/2 s^-1)

Answer: (mol^-1/2 L^1/2s^-1), (mol L^-1 s^-1)

(7) The addition of a catalyst during a chemical reaction alters which of the following quantities?

[A] Enthalpy

[B] Activation energy

[C] Entropy

[D] Internal energy

Answer: Activation energy

(8)

Consider the following statements :

(i) increase in concentration of the reactant increases the rate of a zero order reaction.

(ii) rate constant k is equal to collision frequency A if E_a = 0

(iii) rate constant k is equal to collision frequency A if E_a = °

(iv) a plot of ln(k) vs T is a straight line

(v) a plot of ln (k) vs 1/T is a straight line with a positive slope.

Correct statements are

[A] (ii) only

[B] (ii) and (iv)

[C] (ii) and (v)

[D] (i), (ii) and (v)

Answer: (ii) only

(9)

In a reversible reaction, the enthalpy change and the activation energy in the forward direction are respectively −x kJ mol⁻¹ and y kJ mol⁻¹ . Therefore , the energy of activation in the backward direction is

a) b) c) d)

[A] ( y −x ) kJ mol⁻¹

[B] ( x + y )J mol⁻¹

[C] ( x −y ) kJ mol⁻¹

[D] ( x + y ) × 103 J mol⁻¹

Answer: ( x + y ) × 103 J mol⁻¹

(10)

What is the activation energy for a reaction if its rate doubles when the temperature is raised from 200K to 400K? (R = 8.314 JK^-1mol^-1)

[A]

234.65 kJ mol⁻¹K⁻¹

[B]

434.65 kJ mol⁻¹K⁻¹

[C]

434.65 J mol⁻¹K⁻¹

[D]

334.65 J mol⁻¹K⁻¹

Answer:
434.65 J mol⁻¹K⁻¹

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