Chemical Kinetics MCQs with Explanations

85.2 min is the correct answer to “Sucrose is converted to a mixture of glucose and fructose in a pseudo first order process under alkaline conditions. The reaction has a half-life of 28.4 min. The time required for the reduction of a 8.0 mM sample of sucrose to 1.0 mM is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

200 is the correct answer to “At T = 300 K, the thermal energy [k B T] in cm -1 is approximately”. This question is standard in competitive examination syllabi for Chemical Kinetics.

In t1/2 ∝ 1/T is the correct answer to “The half-life of a first order reaction varies with temperature according to”. This question is standard in competitive examination syllabi for Chemical Kinetics.

0.1386 min-1 is the correct answer to “For a given first order reaction, the reactant reduces to $${\frac{1}{4}^{{\text{th}}}}$$ its initial value in 10 min. The rate constant of the reaction is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

$$\frac{3}{2}\left( {\frac{{ - d\left[ {{X_3}} \right]}}{{dt}}} \right)$$ is the correct answer to “For the reaction, 2X 3 $$ \rightleftharpoons $$ 3X 2 , the rate of formation of X 2 is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

2 is the correct answer to “The half-life time for a reaction at initial concentrations of 0.1 and 0.4 mol -1 are 200 s and 50 s respectively. The order of the reaction is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

4 × 10-4 s-1 is the correct answer to “For the reaction shown below, the value of k 1 is 1 × 10 -4 s -1 . If the reaction starts from X, the ratio of the concentrations of Y and Z at any given time during the course of the reaction is found to be $$\frac{{\left[ {\text{Y}} \right]}}{{\left[ {\text{Z}} \right]}} = \frac{1}{4}.$$ The value of k 2 is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

k1, k-1 and k1/k-1 increase is the correct answer to “Consider an exothermic reaction, $$A\mathop {\mathop \rightleftharpoons \limits_{{k_{ - 1}}} }\limits^{{k_1}} I$$ As the temperature increases”. This question is standard in competitive examination syllabi for Chemical Kinetics.

28.8 yr and 0.887 g is the correct answer to “1 g of 90 Sr gets converted to 0.953 g after 2 yr. The half-life of 90 Sr, and the amount of 90 Sr remaining after 5 yr are”. This question is standard in competitive examination syllabi for Chemical Kinetics.

2kb [NO]2[O2] is the correct answer to “The reaction, 2NO(g) + O 2 (g) → 2NO 2 (g) proceeds via the following steps: NO + NO \[\xrightarrow{{{{\text{K}}_{\text{a}}}}}\] N 2 O 2 N 2 O 2 \[\xrightarrow{{{{\text{K}}_{{\text{a'}}}}}}\] NO + NO N 2 O 2 + O 2 \[\xrightarrow[{\left( {{\text{slow}}} \right)}]{{{{\text{k}}_{\text{b}}}}}\] NO 2 + NO 2 The rate of this reaction is equal to”. This question is standard in competitive examination syllabi for Chemical Kinetics.

$$\left[ A \right] = {\left[ A \right]_0}{e^{ - {k_a}t}}$$ is the correct answer to “A reaction proceeds through the formation of an intermediate B in a unimolecular reaction \[A\xrightarrow{{{k_a}}}B\xrightarrow{{{k_b}}}C\] The integrated rate law for this reaction is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

102 is the correct answer to “In a homogeneous catalytic reaction, 1.0 M of a substrate band 1.0 μM of a catalyst yields 1.0 mM of a product in 10 s. The turnover frequency (TOF) of the reaction (S -1 ) is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

2, 1, 1 is the correct answer to “For the reaction, P + Q + R → S, experimental data for the measured initial rates is given below: Expt. Initial conc. P (M) Initial conc. Q (M) Initial conc. R (M) Initial rate (m/s) 1 0.2 0.5 0.4 8.0 × 10 -5 2 0.4 0.5 0.4 3.2 × 10 -4 3 0.4 2.0 0.4 1.28 × 10 -3 4 0.1 0.25 1.6 4.0 × 10 -5 The order of the reaction with respect to P, Q and R respectively, is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

a plot of 1/[A] versus t is a straight line is the correct answer to “A reaction follows second order rate law, $$\frac{{ - d\left[ A \right]}}{{dt}} = k{\left[ A \right]^2},$$ if”. This question is standard in competitive examination syllabi for Chemical Kinetics.

2 is the correct answer to “The half-life (t 1/2 ) for the hydrolysis of an ester varies with the initial concentration of the reactant ([E] 0 ) as follows: [E] 0 /10 mol/L 5.0 4.0 3.0 t 1/2 /s 240 300 400 The order of the reaction is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

24 kcal/mol is the correct answer to “The specific rate constant of decomposition of a compound is represented by $$\ln k = 5.0 - \frac{{12000}}{T}$$ The activation energy of decomposition foe this compound at 300 K is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

k1 ≪ k2 is the correct answer to “In a consecutive first order reaction, (where k 1 and k 2 are the respective rate constants) species B has transient existence. Therefore,”. This question is standard in competitive examination syllabi for Chemical Kinetics.

1 × 107 s-1 is the correct answer to “The fluorescence life time of a molecule in solution is 10 ns. If the fluorescence quantum yield is 0.1, the rate constant of fluorescence decay is”. This question is standard in competitive examination syllabi for Chemical Kinetics.

2 is the correct answer to “The value of the rate constant for the gas phase reaction, 2NO 2 + F 2 → 2NO 2 F is 38 dm 3 mol -1 s -1 at 300K. The order of the reaction is”. This question is standard in competitive examination syllabi for Chemical Kinetics.