Chemical Kinetics of Parallel, Consecutive and Reversible Reactions - MCQ Questions for CSIR UGC NET & GATE - Download PDF

Parallel, Consecutive and Reversible Reactions
MCQs for CSIR NET & GATE

Chemical Kinetics
Topicwise Assignment-4

QUIZ              PDF

Q1. Listed in the table are forward and reverse rate constants for the reaction

Select the correct statement
(a) reaction is exothermic and value of equilibrium constant (K_eq) at 1400 K is 3.79 x 10^-6
(b) reaction is endothermic and value of K_eq at 1400K is 2.63 x 10⁵
(c) reaction is exothermic and value of K_eq at 1400K is 2.63 x 10⁵
(d) reaction is endothermic and value of K_eq at 1400K is 9.28 x 10⁵

Q2. A decomposes as

the rate of appearance of B, taking 2M concentration of A at any time t is equal to
(a) 2x10^-3 M s^-1
(b) 4x10^-3 M s^-1
(c) 8x10^-3 M s^-1
(d) None of these

Common data for Q3 and Q4
For opposing reaction given below

The forward reaction has values Ea = 100 KJ mol^-1 and A = 1.0 x 1010 M^-1 s^-1. The equilibrium concentration of A, B, C and D are 1.0 M, 2.0 M, 5.0 M and 4.0 respectively at 700 K

Q3. The values of k₁ and k₂ respectively at this temperature are

[GATE 2003]

(a) 20 M^-1 s^-1 and 2.0 M^-1 s^-1
(b) 345 M^-1 s^-1 and 34.5 M^-1 s^-1
(c) 34.5 M^-1 s^-1 and 3.45 M^-1 s^-1
(d) 200 M^-1 s^-1 and 20 M^-1 s^-1

Q4. The rate constant (k₁) for the forward reaction at 1000K is

[GATE 2003]

(a) 5.98x10⁴ M^-1 min^-1
(b) 5.98x10² M^-1 min^-1
(c) 1.00x10³ M^-1 min^-1
(d) 5.98x10⁴ M^-1 s^-1

Q5. Consider an exothermic reaction

[GATE 2006]

as the temperature increases
(a) k₁, k₂ and k₁/k₂ increases
(b) k₁ increases, k₂ decreases and k₁/k₂ increases
(c) k₁, k₂ increases and k₁/k₂ decreases
(d) k₁, k₂ decreases and k₁/k₂ increases

Q6. For a reaction of type

The correct rate expression is
([X]_o and [X] corresponds to the concentration of X at time t=0 and t=t, respectively)

[GATE 2013]

(a) -d[X]/dt = k₁ [X]_o - (k₁+k₂) [X]
(b) -d[X]/dt = (k₁+k₂) [X] - k₂ [X]o
(c) -d[X]/dt = (k₁+k₂) [X]_o - k₁[X]
(d) -d[X]/dt = (k₁-k₂) [X] - k₁[X]_o

Q7. For the parallel first order reaction shown below

[GATE 2009]

The value of k₁ is 1x10^-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 [Y]/[Z] = 1/4.
The value of k₂ is
(a) 1 x 10^-4 s^-1
(b) 2.5 x 10^-5 s^-1
(c) 4 x 10^-4 s^-1
(d) 4 x 10⁴ s^-1

Q8. A gaseous compound A reacts by three independent first order processes with rate constants 2x10^-3, 3x10^-3 and 1.93x10^-3 s^-1 or products B, C and D respectively. If initially pure A was taken in a closed container with P= 8 atm, then the partial pressure of B (in atm) after 100 sec from start of experiment.

(a) 0.288
(b) 0.577
(c) 1.154
(d) None of these

Q9. A catalyst lowers the activation energy for a certain reaction from 83.314 to 75 KJ/mol at 500 K. What will be the rate of a reaction as compare to uncatalyzed reaction? Assume other things become equal.
(a) Double
(b) 28 times
(c) 7.38 times
(d) 7.38 x 10³ times

Q10. The rate law for one of the mechanism of pyrolysis of CH₃CHO at 520 ^oC and 0.2 bar is
Rate = -|k₂(k₁/k₄)^1/2|[CH₃CHO]^3/2
The overall activation energy E, in terms of the rate law is

[NET June 2012]

(a) E_a(2) + E_a(1) + 2 E_a(4)
(b) E_a(2) + 1/2 E_a(1) - E_a(4)
(c) E_a(2) + 1/2 E_a(1) – 1/2 E_a(4)
(d) E_a(2) + 1/2 E_a(1) + 1/2 E_a(4)

Ans Key:

Q1.c Q2.c Q3.b Q4.d Q5.c Q6.b Q7.c Q8.c Q9.c Q10.c

Chapter wise MCQs

Topic wise MCQs