Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 4 Chemical Kinetics with Answers Pdf free download. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. We have provided Chemical Kinetics Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well.

## Chemical Kinetics Class 12 MCQs Questions with Answers

Question 1.
In chemical equation H2 (g) + I2 (g) $$\rightleftharpoons$$ 2HI (g) the equilibrium constant Kp depends on
(a) total pressure
(b) catalyst used
(c) amount of H2 and I2
(d) temperature

Question 2.
If the rate of a reaction is expressed by, rate = A [A]² [B], the order of reaction will be
(a) 2
(b) 3
(c) 1
(d) 0

Question 3.
In a reaction, 2X → Y, the concentration of X decreases from 0.50 M to 0.38 M in 10 min. What is the rate of reaction in Ms-1 during this interval ?
(a) 2 × 10-4
(b) 4 × 10-2
(c) 2 × 10-2
(d) 1 × 10-2

Question 4.
The decomposition of dimethyl ether is a fractional order reaction. The rate is given by rate =k(PCH3OCH3)3/2. If the pressure is measured in bar and time in minutes, then what are the units of rate and rate constant?
(a) bar min-1, bar2 min-1
(b) bar min-1, bar1/2 min-1
(c) bar1/2 min-1, bar2 min-1
(d) bar min-1, bar1/2 min-1

Answer: (b) bar min-1, bar1/2 min-1

Question 5.
A reaction in which reactants (R) are converted into products (P) follows second order kinetics. If concentration of R is increased by four times, what will be the increase in the rate of formation of P?
(a) 9 times
(b) 4 times
(c) 16 times
(d) 8 times

Question 6.
Which of the following, is an example of a fractional order reaction?
(a) NH4NO2 → N2 + 2H2O
(b) NO + O3 → NO2 + O2
(c) 2NO + Br2 → 2NOBr
(d) CH3CHO → CH4 + CO

Answer: (d) CH3CHO → CH4 + CO

Question 7.
The unit of rate constant for the reaction
2H2 + 2NO → 2H2O + N2
which has rate = K|H2||NO|², is
(a) mol L-1 s-1
(b) s-1
(c) mol-2 L² s-1
(d)mol L-1

Question 8.
Fora reaction x + y → z, rate ∝ |X|. What is (i) moleculariiy and (ii) order of reaction?
(a) (i)2, (ii) 1
(b) (i)2,(ii) 2
(c) (i) 1, (ii) 1
(d) (i) 1, (ii) 2

Question 9.
For a reaction nx – y → z the rate of reaction becomes twenty seven times when the concentration of X is increased three times. What is the order of the reaction?
(a) 2
(b) 1
(c) 3
(d) 0

Question 10.
The rate constant of a reaction depends upon
(a) temperature of the reaction
(b) extent of the reaction
(c) initial concentration of the reactants
(d) the time of completion of reaction

Answer: (d) the time of completion of reaction

Question 11.
The chemical reaction, 2O3 → 3O2 proceeds as
O3 $$\rightleftharpoons$$ O2 + |O| (fast)
|O| + O3 → 2O2 (slow)
The rate law expression will be
(a) Rate = k [O] [O3]
(b) Rate = k [O3]² [O2]-1
(c) Rate = k [O3
(d) Rate = k [O2] [O]

Answer: (b) Rate = k [O3]² [O2]-1

Question 12.
The unit of rate and rate constant are same fora
(a) zero order reaction
(b) first order reaction
(c) second order reaction
(d) third order reaction

Question 13.
The number of molecules of the reactants taking part in a single step of the reaction is indicative of
(a) order of a reaction
(b) molecuiarity of a reaction
(c) fast step of the mechanism of a reaction
(d) half-life of the reaction

Answer: (b) molecuiarity of a reaction

Question 14.
Fora unimolecular reaction
(a) the order and molecuiarity of the slowest step are equal to one
(b) molecuiarity of the reaction can be zero, one or two
(c) molecuiarity of the reaction can be determined only experimentally
(d) more than one reacting species are involved in one step

Answer: (a) the order and molecuiarity of the slowest step are equal to one

Question 15.
The overall rate of a reaction is governed by
(a) the rate of fastest intermediate’step
(b) the sum total of the rates of all intermediate steps
(c) the average of the rates of all the intermediate steps
(d) the rate of slowest intermediate step

Answer: (d) the rate of slowest intermediate step

Question 16.
The order of reaction is decided by
(a) temperature
(b) mechanism of reaction as well as relative concentration of reactants
(c) molecularity
(d) pressure

Answer: (b) mechanism of reaction as well as relative concentration of reactants

Question 17.
Rate constant in case of first order reaction is
(a) inversely proportional to the concentration units
(b) independent of concentration units
(c) directly proportional to concentration units
(d) inversely proportional to the square of concentration units

Answer: (b) independent of concentration units

Question 18.
Half life period of a first order reaction is 10 min. What percentage of the reaction will be completed in 100 min?
(a) 25%
(b) 50%
(c) 99.9%
(d) 75%

Question 19.
In pseudo unimolecular reactions
(a) both the reactants are present in low concentration
(b) both the reactants are present in same concentration
(c) one of the reactant is present in excess
(d) one of the reactant is non-reactive

Answer: (c) one of the reactant is present in excess

Question 20.
A first order reaction takes 40 min for 30% decomposition. What will be t12?
(a) 77.7 min
(b) 52.5 min
(c) 46.2 min
(d) 22.7 min

Question 21.
A first order reaction has a rate constant 1.15 × 10-3s-1. How long time will 5 g of this reactant take to reduce to 3 g?
(a) 444 s
(b) 400 s
(c) 528 s
(d) 669 s

Question 22.
Radioactive disintegration is an example of
(a) zero order reaction
(b) first order reaction
(c) second order reaction
(d) third order reaction

Question 23.
A plot of log (a – x) against time t is a straight line. This indicates that the reaction is of
(a) zero order
(b) first order
(c) second order
(d) third order

Question 24.
Rate of which reaction increases with temperature?
(a) Exothermic reaction
(b) Endothermic reaction
(c) (a) and (b) both
(d) None of the above

Answer: (c) (a) and (b) both

Question 25.
The activation energy in a chemical reaction is defined as
(a) the difference in energies of reactants and products
(b) the sum of energies of reactants and products
(c) the difference in energy of intermediate complex with the average energy of reactants and products
(d) the difference in energy of intermediate complex and the average energy of reactants