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Free download in PDF Class 12 Chemistry Chapter 4 Chemical Kinetics Multiple Choice Questions (MCQs) and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams like NEET, AIIMS, JIPMER etc. These short solved questions or quizzes are provided by Gkseries./p>
(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
(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
(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
(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
(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
(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
(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
(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
(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%
(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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