Class 12 Chemistry Chapter 4 Chemical Kinetics MCQs | Class 12 Chemistry Chapter 4 Chemical Kinetics Multiple Choice Questions (MCQs) and Answers

Questions
1 Which of the following observations is incorrect about the order of a reaction?
A Order of a reaction is always a whole number
B The stoichiometric coefficient of the reactants doesn’t affect the order
C Order of reaction is the sum of power to express the rate of reaction to the concentration terms of the reactants
D Order can only be assessed experimentally

Answer:Order of a reaction is always a whole number
2 The rate constant of  zero-order reactions has the unit
A s-1
B mol L-1 s-1
C L2 mol-2 s-1
D L mol-1 s-1

Answer:mol L-1 s-1
3 In the reaction 2A + B → A2B, if the concentration of A is doubled and that of B is halved, then the rate of the reaction will
A increase 2 times
B increase 4 times
C decrease 2 times
D remain the same

Answer: increase 2 times
4 When the rate of the reaction is equal to the rate constant, the order of the reaction is
A zero order
B first order
C second order
D third order

Answer: zero order
5 A substance ‘A’ decomposes by a first-order reaction starting initially with [A] = 2.00M and after 200min, [A] becomes 0.15M. For this reaction t1/2 is
A 53.72 min
B 50.49 min
C 48.45 min
D 46.45 min

Answer: 53.72 min
6 In the Haber process for the manufacture of ammonia the following catalyst is used
A Platinized asbestos
B Iron with molybdenum as a promoter
C Copper oxide
D Alumina

Answer:Iron with molybdenum as a promoter
7 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

Answer:the difference in energy of intermediate complex and the average energy of reactants
8 Rate of which reaction increases with temperature?
A Exothermic reaction
B Endothermic reaction
C (a) and (b) both
D None of the above

Answer:(a) and (b) both
9 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

Answer:first order
10 Radioactive disintegration is an example of
A zero order reaction
B first order reaction
C second order reaction
D third order reaction

Answer:first order reaction
11 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

Answer:444 s
12 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

Answer: 77.7 min
13 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: one of the reactant is present in excess
14 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%

Answer:99.9%
15 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:independent of concentration units
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: mechanism of reaction as well as relative concentration of reactants
17 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: the rate of slowest intermediate step
18 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:the order and molecuiarity of the slowest step are equal to one
19 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: molecuiarity of a reaction
20 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

Answer: zero order reaction

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