# CBSE Class 12 Chemistry Chapter 4 Chemical Kinetics MCQs

## CBSE Class 12 Chemistry Chapter 4 Chemical Kinetics MCQs

CBSE Class 12 Chemistry Chapter 4 Chemical Kinetics MCQs. These MCQs of Chemical Kinetics chapter are prepared by our Chemistry Expert. By practising following MCQs, students will be able to quickly revise all the concepts of the Chemical Kinetics. Additionally, CBSE Class 12 Chemistry Chapter 4 Chemical Kinetics MCQs will be helpfull for JEE And NEET Aspirants.

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### CBSE Class 12 Chemistry Chapter Chemical Kinetics MCQs (Set A)

1. Rise in temperature leads to a large increase in the rate of a reaction is due to
(a) increase in the number of collisions
(b) None
(c) The shortening of mean free path
(d) the lowering of activation energy
Answer: The shortening of mean free path

2. In a reversible reaction, the catalyst
(a) activation energy of the backward reaction Increases
(b)None
(c)Forward and backward reaction ,activation energy decreases
(d)activation energy of forward reaction get
decrease
Answer: Forward and backward reaction ,activation energy decreases

3. Following mechanism has been proposed for a reactions,
2A + B —D + E ;
A + B —C + D …..(Slow);
A + C —E …….(fast).
For the given reaction Find the rate law expression:

(a) r = K[A]2
(b) r = K[A]2[B]
(c)r=K[A]
(d) none

4. For a zero order reaction. Which of the following statement
is false :

(a) The rate is independent of the temperature of the reaction
(b) The rate is independent of the concentration of the
reactants
(c) Both A and B
(d) None
Answer: The rate is independent of the temperature of the reaction

5. The first order rate constant k is related to temperature as
log k = 15.0 – (10^6 divide by T). Which of the following pair of value
is correct?

(a) A = 10^15 and E = 1.9 × 10^4KJ
(b) A = 10 and E = 4 KJ
(c) none
(d) A = 10^–15 and E = 1.9 × 10^4 KJ
Answer: A = 10^15 and E = 1.9 × 10^4KJ

6. When a graph between log K and 1/T is drawn a straight
line is obtained. The temperature at which line cuts x-axis and y-axis

(a) 0, Ea
/2.303 R log A
(b) 0, Ea
/(R ln A)
(c) 0, log A
(d) None of these
7. 2 and 3 are the temperature coefficients of reaction I and reaction II respectively. Both have same speed at 25°C and show I order kinetics. At 75°C, the ratio of rates of reactions is :
(a) 7.6
(b) 5.6
(c) 6.6
(d) 8.6

8. A reaction of the type A + 2B + C — D occurs by following
mechanism . Find order if reaction
A + B — X rapid equilibrium
X + C — Y Slow
Y + B — D Fast

(a) 1
(b) 2
(c) 3
(d) Non determinable

### CBSE Class 12 Chemistry Chapter Chemical Kinetics MCQs (Set B)

1. The rate of a chemical reaction
(a) Increases as the reaction proceeds
(b) Decreases as the reaction proceeds
(c) Decreases or increases
(d) Remains constant as the reaction proceeds
Answer: Decreases as the reaction proceeds

2. Substance reacts with each other at rate depends on its
(a) Atomic weight
(b) Equivalent weight
(c) Molecular weight
(d) Active mass

3. For an elementary reaction 2A + B — products, if A is doubled and the active mass of B is kept constant. The
rate of reaction will then

(a) Increase 2 times
(b) Increase 4 times
(c) Decrease 2 times
(d) Decrease 4 times

4. The concentration of ,for a first order reaction:
(a) Is independent of time
(b) Varies linearly with time
(c) Varies exponentially with time
(d) None

5. In a first order reaction the concentration of reactant
decreases from 800mol / dm^3
to 50mol / dm^3
in
2×10^2
sec . Find ,sec ^1 rate of reaction

(a) 2×10^4
(b) 3.45 ×10^5
(c) 1.386 ×10^2
(d) 2×10^2

6. The half – life of a radioactive isotope is three hours. If the
initial mass of isotope were 256 g, the mass of it remaining
undecayed after 18 hours would be :

(a) 16.0 g
(b) 4.0 g
(c) 8.0 g
(d) 12.0 g

7. From the following which is a second order reaction
(a) K =5.47 ×10^4
sec ^1
(b) K =3.9 ×10^3 mole lit sec^1
(c) K =3.94 ×10^4
lit mole-1 sec^1
(d) K = 3.98 ×10^5
lit mole-2 sec^1
lit mole-1 sec^1

8. On increasing the temperature, the rate of the reaction
increases because of

(a) Decrease in the number of collisions
(b) Decrease in the energy of activation
(c) Effective collisions number get Increase
(d) None

### CBSE Class 12 Chemistry Chapter Chemical Kinetics MCQs (Set C)

1. A sample of a radioactive substance undergoes
80% decomposition in 345 minutes. Its half-life is
______ minutes.

(A) ln 2 /ln 5×345
(B) ln 5 /ln 2 ×345
(C) ln 5 /ln 4×345
(D) ln 4 /ln 5 ×345

2. The half-life of a second order process,
2A — products, is

(A) Independent of initial concentration
(B) Directly proportional to initial concentration
of A
(C) Inversely proportional to initial concentration
of A
(D) Inversely proportional to square of initial
concentration
Answer: Inversely proportional to initial concentration
of A

3. At 500 K, the half-life period of a gaseous reaction at an initial pressure of 80 KPa is 350 sec. When the half-life period is 175 sec and pressure is 40Kpa. The order of the reaction is
(A) 0
(B) 1
(C) 2
(D) 6

4. For a reaction Ea =0 and k = 3.2 × 10^4 s–1 at 300K. At 310 K the value of K would be
(A) 6.4 × 10^4 s–1
(B) 3.2 × 10^4 s–1
(C) 3.2 × 10^8 s–1
(D) 3.2 × 10^5 s–1

5. For N2(g) + 3H2(g) → 2NH3(g) + 22 kcal, Ea for the reaction is 70 kcal, Hence, the activation energy for
2NH3(g) → N2(g) + 3H2(g) is

(A) 92 kcal
(B) 70 kcal
(C) 48 kcal
(D) 22 kcal

6. In a zero-order reaction, for every 10°C rise of
temperature, the rate is doubled. If the temperature is increased from 10∘C to 100∘C, the rate of the
reaction will become

(A) 256 times
(B) 512 times
(C) 64 times
(D) 128 times

7. During a chemical reaction formed by addition of a catalyst alters which of the following quantities?
(A) Enthalpy
(B) Activation energy
(C) Entropy
(D) Internal energy

8. For a reaction, activation energy 𝐸𝑎 = 0 and the rate constant at 200 K is 1.6 × 10^6 s−1.The rate constant at 400 K will be
[Given that gas constant
𝑅 = 8.314 J K−1mol−1 ]

(A) 3.2 × 10^4 s−1
(B) 1.6 × 10^6 s−1
(C) 1.6 × 10^3 s−1
(D) 3.2 × 10^6 s−1

### CBSE Class 12 Chemistry Chapter Chemical Kinetics MCQs (Set D)

1. Forward reaction activation energy is
50kCal. The energy of activation of its backward
reaction is

(A) Equal to 50kCal
(B) Greater than 50kCal
(C) Less than 50kCal
(D) Either greater or less than 50kCal
Answer: Either greater or less than 50kCal

2. An exothermic reaction has an activation
energy 30 kJ mol–1
During reaction, if (∆E) is –20 kJ, then the activation energy for

the reverse reaction is
(A) 10 kJ
(B) 20 kJ
(C) 50 kJ
(D) –30 kJ

3. The rate of first order reaction is 0.04 mol. L–1 s–1 at
10 seconds and after initiation of the reaction 0.03mol L^1s^1 at 20 seconds. Find half-life period of the reaction
(A) 44.1 s
(B) 54.1 s
(C) 24.1 s
(D) 34.1 s

4. Rate expression of a chemical change is
dx/dt
=
k[A]2
[B][C]0. The order of reaction is

(A) 3
(B) 2
(C) 1
(D) zero
5. For a first order reaction,
(A) t0.75 = 3t0.5
(B) t0.75 = 2t0.5
(C) t0.75 = 1.5t0.5
(D) None

6. For the reaction, A + B — 2C + D, which one is the
incorrect statement?

(A) None
(B) Rate of disappearance of A= Rate of
appearance of D
(C) Rate of disappearance of B = 2 × rate of
appearance of C
(D) Rate of disappearance of B =
12× rate of appearance of C
Answer: Rate of disappearance of B = 2 × rate of
appearance of C

7.For the reaction: H2(g) + I2(g) — 2HI(g), the rate of
disappearance of H2, is 1.0 × 10–4 mol L–1
s–1.The rate of appearance of HI will be

(A) 1.0 × 10^–4 mol L–1 s–1
(B) 0.50 × 10^–4 mol L–1 s–1
(C) 2.0 × 10^–4 mol L–1 s–1
(D) 4.0 × 10^–4 mol L–1 s–1
Answer: 2.0 × 10^–4 mol L–1 s–1

8. The rate of the reaction, A + B + C — Products, is
given by –d[A]/dt
= k[A]1/2[B]1/3[C]1/4. The order of the reaction is

(A) 1/2
(B) 5/4
(C) 1
(D) 2

### CBSE Class 12 Chemistry Chapter Chemical Kinetics MCQs (Set E)

1. The rate constant, the activation energy and the Arrhenius
parameter (a) of a chemical reaction at 25°C are 3.0 × 10^–4 s–1,104.4 kJ mol^–1 and 6.0 × 1014s^–1 respectively. The value of the rate constant at T to infinity is
(a) 2.0 × 10^18 s–1
(b) 6.0 × 10^14 s–1
(c) infinity
(d) 6 × 10^30s–1
2. If a I-order reaction is completed to the extent of 60% and
20% in time intervals, t1and T2
,what is the ratio,t1 : t2 ?
(a) 6.32
(b) 5.58
(c) 4.11
(d) 8.33
3. A gaseous hypothetical chemical equation
2A —-4B +C is carried out in a closed vessel. The
concentration of B is found to increase by 5 ×10^3 mol l ^1
in 10 second. Find rate of appearance of B is
(a) 5 ×10^2 mol l^1
sec ^1
(b) 5 ×10^5 mol l ^1
sec ^1
(c) 6 ×10^5mol l ^1
sec ^1
(d) 4 ×10^4 mol l^1
sec^1
sec ^1
4. A substance (initial concentration ‘a’) reacts
according to zero order kinetics. Find how much time taken for the completion of reaction is
(A) a/k
(B) a/2k
(C) k/a
(D) 2k/a
5. N2O5(g) ,decomposition is given that
2N2O5(g) → 4NO2(g) + O2(g) activation energy =
Ea
N2O5(g) → 2NO2(g) + 1
2 O2(g)
activation energy = Ea’ then
(A) Ea = 2Ea’
(B) Ea > Ea’
(c) Ea < Ea’
(D) Ea = Ea’
6. Rate expression of a chemical change is
dx/dt= k[A]2[B][C]0. The order of reaction is
(A) 3
(B) 2
(C) 1
(D) zero