Chemical Kinetics MCQ with Answers for IIT JAM 2023

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Chemical Kinetics MCQ with Answers for IIT JAM 2023


1. Select the incorrect statement

(a) Larger the value of Ea, smaller the value of rate constant (k)
(b) Larger the value of Ea, greater is the effect on the value of k for a given temperature change.
(c) At lower temperature, increase in temperature causes more change in the value of k than at higher temperature
(d) k is affected by change in concentration.

Answer

Answer: (d)


2. The increase in rate of a reaction with rise in temperature is mainly due to

(a) increase in collision frequency
(b) lowering of activation energy
(c) increase in number of effective collisions
(d) increase in activation energy

Answer

Answer: (c)


3. The rate constant of a unimolecular reaction was 2.66 × 10-3 s-1 and 2.2 × 10-1 s-1 at T= 120 K and 360 K respectively. The rate constant (in s-1 units) at 240 K would be

(a) 2.4 x 10-2
(b) 2.4 x 10-1
(c) 4.8 x 10-2
(d) 1.8 x 10-3

Answer

Answer: (a)


4. The arrhenius parameters for the thermal decomposition of NOCI, 2NOCI(g) → 2NO(g) + Cl2(g), are A = 1013 M-1 s-1, Ea = 105 kJ mol-1 and RT = 2.5 kJ mol-1. The enthalpy (in kJ mol-1) of the activated complex will be

(a) 110
(b) 105
(c) 102.5
(d) 100

Answer

Answer: (d)


5. In the Lindeman mechanism of unimolecuair reactions, the observed order at low concentration is

(a) 0.5
(b) 1
(c) 1.5
(d) 2

Answer

Answer: (d)


6. According to Arrhenius equation (K = rate constnat and T = temperature)

(a) In K decreases linearly with 1/T
(b) In K decreases linearly with T
(c) In K increases linearly with 1/T
(d) In K increases linearly with T

Answer

Answer: (a)


7. A reaction of first-order completed 90% in 90 minutes, hence, it is completed 50% in approximately

(a) 50 min
(b) 54 min
(c) 27 min
(d) 62 min

Answer

Answer: (c)


8. T50 (Half-life period) of first-order reaction is 10 minute. Starting with 10 mol L-1,  rate after 20 minute is :

(a) 0.0693 mol L-1 min-1
(b) 0.0693 × 2.5 mol L-1 min-1
(c) 0.0693 × 5 mol L-1 min-1
(d) 0.0693 × 10 mol L-1 min-1

Answer

Answer: (b)


9. For the first-order reaction Tav (average life), T50 and T75 in the increasing order are :

(a) T50 <  Tav < T75
(b) T50 < T75 < Tav
(c) Tav < T50 < T75
(d) Tav = T50 < T75

Answer

Answer: (a)


10. If (dx/dt) = k [H+]n and rate becomes 100 times when pH changes from 2 to 1. Hence, order is :

(a) 1
(b) 2
(c) 3
(d) 0

Answer

Answer: (b)


11. If the fermentation of sugar in an enzymatic solution that is 0.12 M, the concentration of the sugar is reduced to 0.06 M in 10 h and to 0.03 M in 20 h. What is the order of the reaction ?

(a) 1
(b) 2
(c) 3
(d) 0

Answer

Answer: (a)


12. Number of natural life times (Tav) required for a first-order reaction to achieve 99.9% level of completion is :

(a) 2.3
(b) 6.9
(c) 9.2
(d) 0.105

Answer

Answer: (b)


13. The time taken for 10% completion of a first order reaction is 20 mins. Then, for 19% completion, the reaction will take

(a) 40 min.
(b) 60 min.
(c) 30 min.
(d) 50 min.

Answer

Answer: (a)


14. Ammonia and oxygen react at higher temperatures as

4NH3(g) + 5O2(g) → 4NO(g) + 6H20 (l )

In an experiment the concentration of NO increases by 1.08 × 10-2 moles litre-1 in 3 seconds.

Which of the following is not correct.

(a) The rate of reaction is 9 × 10-4 moles litre-2 seconds-1
(b) The order of the reaction is 2.
(c) The rate of disappearance of NH3 is 36 × 10-4 moles litre-2 seconds-1
(d) The rate of appearance of H2O is 54 × 10-4 moles litre-2 seconds-1

Answer

Answer: (b)


15. If a reaction is of nth order the half life period. of the initial concentration of reactants.

(a) is independent
(b) varies inversely as (n-1)th power
(c) varies inversely at nth power
(d) varies directly as (n – 1)th power

Answer

Answer: (b)


16. The decomposition of gaseous acetaldehyde at T(K) follows second order kinetics. The half-life of this reaction is 400 s when the initial pressure is 250 Torr. What will be the rate constant (in Torr-1 s-1) and half-life (in s) respectively, if the initial pressure of the acetaldehyde is 200 Torr at the same temperature?

(a) 105 and 500
(b) 10-5 and 400
(c) 10-4 and 400
(d) 10-5 and 500

Answer

Answer: (d)


17. The concentrations of a species A undergoing the reaction A → P is 1.0, 0.5, 0.33, 0.25 mol dm-3 at t = 0, 1, 2 and 3 seconds, respectively. The order of the reaction is

(a) two
(b) one
(c) zero
(d) three

Answer

Answer: (a)


18. Select the correct statements out of I, II and III for zero order reaction
I: Quantity of the product formed is directly proportional to time
II : Larger the initial concentration of the reactant, greater the half-life period
III : If 50% reaction takes place in 100 minutes, 75% reaction take place in 150 minutes.

(a) I only
(b) I and II only
(c) II and III only
(d) I, II and III

Answer

Answer: (d)


19. The rate constant of a reaction does not depend upon:
(a) temperature
(b) activation energy
(c) catalyst
(d) concentration of reactants and products

Answer

Answer: (d)


20. The rate of reaction that does not involve gases, is not dependent on:

(a) pressure
(b) temperature
(c) concentration
(d) catalyst

Answer

Answer: (a)


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