MCQ Questions for Class 12 Chemistry Chapter 4 Chemical Kinetics with Answers
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Chemical Kinetics Class 12 MCQs Questions with Answers
Solving the Chemical Kinetics Multiple Choice Questions of Class 12 Chemistry Chapter 4 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Chemical Kinetics Class 12 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 4 Chemistry Class 12 and cross-check your answers during preparation.
Question 1.
A first order reaction has a half life period of 34.65 seconds. Its rate constant is
(a) 2 × 10-2 s-1
(b) 4 × 10-4 s-1
(c) 20 s-1
(d) 2 × 10-4 s-1
Answer
Answer: (a) 2 × 10-2 s-1
Question 2.
If a graph is plotted between In k and 1/T for the first order reaction, the slope of the straight line so obtained is given by
(a) –\(\frac { E_a }{R}\)
(b) \(\frac { E_a }{2.303 R}\)
(c) \(\frac { 2.303 }{E_a.R}\)
(d) \(\frac { E_a }{2.303}\)
Answer
Answer: (a) –\(\frac { E_a }{R}\)
Question 3.
The unit of rate constant for a zero order reaction is
(a) mol L-1s-1
(b) s-1
(c) L mol-1s-1
(d) L2mol-2s-1
Answer
Answer: (a) mol L-1s-1
Question 4.
A catalyst increases the speed of a chemical reaction by
(a) increasing activation energy
(b) decreasing activation energy
(c) increasing reactant energy
(d) decreasing threshold energy
Answer
Answer: (b) decreasing activation energy
Question 5.
The units of the rate constant for the second order reaction are:
(a) mol-1 litre s-1
(b) mol litre-2 s-1
(c) s-1
(d) mol litre-1 s-1
Answer
Answer: (a) mol-1 litre s-1
Question 6.
The value of k for a reaction is 2.96 × 10-30 s-1. What is the order of the reaction?
(a) Zero
(b) 3
(c) 2
(d) 1
Answer
Answer: (d) 1
Question 7.
A reaction is found to be of second order with respect to concentration of carbon monoxide. If concentration of carbon monoxide is doubled, the rate of reaction will
(a) triple
(b) increase by a factor of 4
(c) double
(d) remain unchanged
Answer
Answer: (b) increase by a factor of 4
Question 8.
If the concentrations are expressed in mol litre-1 and time in s, then the units of rate constant for the first-order reactions are
(a) mol litre-1 s-1
(b) mol-1 litre s-1
(c) s-1
(d) mol² litre-2 s-1
Answer
Answer: (c) s-1
Question 9.
The half life of a first order reaction having rate constant 200 s-1 is
(a) 3.465 × 10-2 s
(b) 3.465 × 10-3 s
(c) 1.150 × 10-2 S
(d) 1.150 × 10-3 S
Answer
Answer: (b) 3.465 × 10-3 s
Question 10.
The rate of a reaction is 1.209 × 10-4L² mol-2s-1. The order of the reaction is:
(a) zero
(b) first
(c) second
(d) third
Answer
Answer: (d) third
Question 11.
A catalyst increases the rate of a reaction by
(a) increasing threshold energy
(b) increasing activation energy
(c) activating the reactants
(d) lowering activation energy
Answer
Answer: (d) lowering activation energy
Question 12.
Time required for 100% completion of a zero order reaction is:
(a) t100% = a/k
(b) t100% = a.k
(c) t100% = a/2k
(d) None of these
Answer
Answer: (a) t100% = a/k
Question 13.
Arrhenius equation is represented by:
(a) k = AeEa/RT
(b) k = Ae-Ea/RT
(c) t1/2 = 0.693/k
(d) None of these
Answer
Answer: (b) k = Ae-Ea/RT
Question 14.
The overall order of a reaction, which has the rate expression: Rate = AC[A]1/2[B]3/2 is:
(a) First order
(b) Second order
(c) Third order
(d) Zero order
Answer
Answer: (b) Second order
Question 15.
If half life period of a first order reaction is 100 seconds. Then rate constant will be:
(a) 6.93 × 10-3 second-1
(b) 6.93 × 10-2 second-1
(c) 0.693 second-1
(d) 6.93 second-1
Answer
Answer: (a) 6.93 × 10-3 second-1
Question 16.
If rate constant for a reaction is mole litre-1 second-1, then order of reaction is:
(a) Zero order
(b) First order
(c) Second order
(d) None of these
Answer
Answer: (a) Zero order
Question 17.
Identify the order of reaction from the given rate constant k = 2.6 × 10-4 L mol-1 s-1
(a) First
(b) Zero
(c) Second
(d) None of these
Answer
Answer: (c) Second
Question 18.
For a reaction: N2 + 3H2 → 2NH3, the rate of reaction with respect to NH3 will be:
(a) –\(\frac{d\left[\mathrm{NH}_{3}\right]}{d t}\)
(b) –\(\frac{d[NH_3]^2}{d t}\)
(c) +\(\frac { 1 }{10}\) \(\frac { d[NH_3] }{dt}\)
(d) –\(\frac { 1 }{10}\) \(\frac { d[NH_3] }{dt}\)
Answer
Answer: (c) +\(\frac { 1 }{10}\) \(\frac { d[NH_3] }{dt}\)
Question 19.
Half life period of a first order reaction depends upon:
(a) Concentration of reactants
(b) Concentration of products
(c) Rate constant of reaction
(d) None of these
Answer
Answer: (c) Rate constant of reaction
Question 20.
Half life period of a first order reaction is:
(a) directly proportional to the initial concentration of the reactant
(b) half of the rate constant
(c) same for all reactions
(d) independent of the initial concentration of the reactants
Answer
Answer: (d) independent of the initial concentration of the reactants
Assertion and Reason Type Questions
The questions given below consist of an assertion and a reason. Use the following key to choose the appropriate answer.
(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is correct, Reason (R) is wrong statement.
(d) Assertion (A) is wrong, but Reason (R) is correct statement.
Question 21.
Assertion: Rate of reaction increases with increase in temperature.
Reason: Number of collisions increases – with increase in temperature.
Answer
Answer: (a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
Question 22.
Assertion: Reactions of higher order are rare.
Reason: The chances of simultaneous multimolecular collisions are extremely small.
Answer
Answer: (a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
Question 23.
Assertion: The half life period for a first order reaction is independent of initial concentration of reactants.
Reason: For first order reaction, t1/2 = \(\frac { 0.693 }{k}\)
Answer
Answer: (a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
Question 24.
Assertion: For the first order reaction the units of rate constant are time-1.
Reason: The rate of first order reaction remains constant throughout.
Answer
Answer: (c) Assertion (A) is correct, Reason (R) is wrong statement.
Question 25.
Assertion: For a first order reaction, graph of [A] vs. t is a straight line.
Reason: For first order reaction, k = \(\frac { 2.303 }{t}\) log \(\frac { [R]_0 }{[R]}\)
Answer
Answer: (d) Assertion (A) is wrong, but Reason (R) is correct statement.
Question 26.
Assertion: For complex reactions molecularity and order are not same.
Reason: Order of a reaction may be zero.
Answer
Answer: (b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
Question 27.
Assertion: A catalyst increases the rate of a reaction.
Reason: A catalyst forms an activated complex of lower potential energy.
Answer
Answer: (a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
Question 28.
Assertion: The molecularity of the reaction
H2 + Br2 → 2HBr is 2.
Reason: Order of the reaction is 3/2.
Answer
Answer: (c) Assertion (A) is correct, Reason (R) is wrong statement.
Question 29.
Assertion: For the reaction:
RCl + NaOH (aq) → ROH + NaCl, the rate of reaction is reduced to half when the concentration of RCl is reduced to half.
Reason: The rate of reactions is represented by k[RCl], i.e. it is a first order reaction.
Answer
Answer: (c) Assertion (A) is correct, Reason (R) is wrong statement.
Question 30.
Assertion: Photochemical reactions always occur in the presence of light.
Reason: Photochemical reactions even with, ΔG = +ve occur.
Answer
Answer: (b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
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