CHEMICAL KINETICS MCQs

By: Prof. Dr. Fazal Rehman | Last updated: May 23, 2025

1. : The rate at which a substance reacts depends on its
(A) Molecular mass
(B) Atomic mass unit
(C) Atomic mass
(D) Active mass

2. : The branch of chemistry which deals with the rate and mechanism of a reaction is called _____ .
(A) Chemical kinetics
(B) Classical thermodynamics
(C) Wave mechanism
(D) Photochemistry

3. : The change in the concentration of the reactant or product per unit time is called
(A) Rate of reaction
(B) Molecularity of the reaction
(C) Rate constant
(D) Order of the reaction

4. : Usually the rate of the reaction is expressed as
(A) mol dm⁻³
(B) mol² dm⁻² s⁻¹
(C) mol dm⁻² s⁻¹
(D) mol dm⁻³ s⁻¹

5. : Chemical kinetics is helpful and used to study
(A) Mechanism of reaction
(B) Effect of temperature on reaction rate
(C) Rate of reaction
(D) All of A, B, and C

6. : The reaction in which the rate is independent of concentration is called ____ .
(A) Zero order
(B) First order
(C) Second order
(D) Third order

7. : The Arrhenius equation accounts for the rate of chemical reaction in terms of?
(A) Activation energy
(B) Molecularity of reaction
(C) Order of reaction
(D) Physical state

8. : The dimension for first order rate constant is
(A) s
(B) s mol⁻¹
(C) mol⁻¹ s⁻¹
(D) s⁻¹

9. : The rate constant of a reaction depends on
(A) Concentration of reactants
(B) Concentration of products
(C) Temperature
(D) Pressure

10. : The rate constant of a reaction has same units as the rate of the reaction. The reaction is of
(A) Zero order
(B) First order
(C) Second order
(D) Third order

11. : The rate constant for 3rd order reaction has the dimension of which of the following?
(A) mol⁻² s⁻¹
(B) l⁻¹ mol⁻¹ s⁻¹
(C) mol l⁻¹ s⁻¹
(D) l² mol⁻² s⁻¹

12. : Which factors affect the rate of the reaction?
(A) Concentration
(B) Pressure
(C) Temperature
(D) All of A, B, and C

13. : For a reaction of the type A + B → Products, it is observed that doubling the concentration of A causes the reaction rate to be four times as great, but doubling the amount of B has no apparent effect on the rate. The rate equation is
(A) Rate = k |A|²
(B) Rate = k |A| |B|
(C) Rate = k |A|² |B|
(D) Rate = k |A|² |B|²

14. : Suppose we have a reaction 2A + B → C + D. The rate of the reaction increases eight times when the concentrations of both A and B are doubled. The rate of the reaction increases four times when the initial concentration of only B is doubled. What is the rate expression for the reaction?
(A) r = k |A|² |B|
(B) r = k |A|² |B|²
(C) r = k |A| |B|
(D) r = k |A| |B|²

15. : For an elementary reaction 2A + B → C + D, the molecularity of the reaction is
(A) 4
(B) 3
(C) 2
(D) 1

16. : A second order rate constant has the dimension of which of the following?
(A) dm⁻⁶ mol² s⁻¹
(B) dm³ mol⁻¹ s⁻¹
(C) dm l⁻² s⁻¹
(D) dm³ mol s⁻¹

17. : Which is an acceptable value of the molecularity?
(A) 2.5
(B) 0
(C) 2
(D) 8

18. : Which statement about molecularity is not true?
(A) It cannot be more than 3
(B) It can be obtained from balanced equation
(C) It may or may not be equal to the order of the reaction
(D) It cannot be fraction

19. : From an elementary reaction of the type A + 2B → C + D, what is the order of the reaction?
(A) 2
(B) 3
(C) Cannot be determined
(D) Zero

20. : The following mechanism has been proposed for a reaction 2A + B → D + E:
A + B → C + D (slow),
A + C → E (fast).
What is the rate expression for the reaction?
(A) r = k |A| |B|

21. : For a chemical reaction A → products, the rate of the reaction doubles when the concentration of A is increased by 4 times. What is the order of the reaction?
(A) 0.5
(B) 0
(C) 2
(D) 1

22. : The minimum amount of energy that the reacting molecules must possess at the time of collisions in order to produce effective collisions is called________.
(A) Free energy
(B) External energy
(C) Internal energy
(D) Activation energy

23. : What is the order of reaction of radioactive decay?
(A) Zero
(B) 2
(C) 1
(D) 3

24. : Point out the false statement.
(A) Rate law is an experimental fact whereas law of mass action is theoretical in nature
(B) Order of the reaction is equal to the sum of the exponents of concentration terms in the rate law
(C) Rate law is more informative than law of mass action
(D) Law is forever different from the expression of law of mass action

25. : For a hypothetical reaction A + B → Products, the rate law is r = k |B| |A|². What is the order of the reaction?
(A) 2
(B) 3
(C) 0
(D) 1

26. : The hydrolysis of methyl acetate reaction is of
(A) Zero order
(B) Second order
(C) Third order
(D) First order

27. : Suppose CA is the concentration of A at any time and C₀A is its concentration at t = 0, then for a zero-order reaction of the type A → Products, the rate equation can be written as ______ .
(A) CA – C₀A = 0
(B) CA = C₀A – kt
(C) CA / C₀A = k
(D) CA = C₀A – k

28. : In multistep reaction, which is the slowest step?
(A) Mechanism step
(B) Enthalpy determining step
(C) Rate determining step
(D) None of A, B, and C

29. : The half-life period of any first order reaction
(A) Is independent of the initial concentration
(B) Is half the specific rate constant
(C) Is forever the same whatever the reaction
(D) Is directly proportional to the initial concentration of the reactant

30. : Which methods are/is helpful and used to determine the rate of the reaction?
(A) Polarimetry
(B) Conductometry
(C) Spectroscopy
(D) All of A, B, and C

31. : Which technique is helpful and used to measure absorption of radiation?
(A) Conductometry
(B) Polarimetry
(C) Dilatometry
(D) Spectrophotometry

32. : For the first-order reaction with rate constant k, the half-life period (initial concentration = a) is equal to
(A) 1/ka
(B) 1/ka1/2
(C) 0.693/ka
(D) ln2/k

33. : Why does a catalyst increase the rate of a reaction?
(A) It provides the necessary energy to the colliding molecules to cross energy barrier
(B) It provides a different path of lower activation energy
(C) It decreases the order of the reaction
(D) It decreases the heat of the reaction

34. : Chemical reactions of the type A → B → C (with rate constants k1 and k2) are called
(A) Pseudo chemical reactions
(B) Consecutive reactions
(C) Parallel reactions
(D) Fast reactions

35. : In the dilatometric method, the rate of reaction is measured by change in
(A) Pressure
(B) Conductance
(C) Concentration
(D) Volume

36. : The rate of reaction between two specific time intervals is called
(A) Rate constant
(B) Instantaneous rate
(C) Average rate
(D) Rate of reaction

37. : The equation for the rate constant is given by k = p Z e^(-Ea/RT). A chemical reaction will proceed more rapidly if there is a decrease in
(A) E (Activation energy)
(B) Z (Collision frequency)
(C) T (Temperature)
(D) P (Steric factor)

38. : The large increase in the rate of a reaction on rise in temperature is due to
(A) The increase in the number of molecules having more than the threshold energy
(B) The decrease in mean free path
(C) The increase in collision frequency
(D) The lowering of activation energy

39. : In the kinetic study of a reaction A → Products, a straight line was observed when a graph between time and 1/C² was plotted. The reaction is
(A) Second order
(B) First order
(C) Zero order
(D) Third order

40. : Which is NOT a true characteristic of a catalytic reaction?
(A) The amount and chemical composition of the catalyst remains unchanged after the reaction
(B) The catalyst shifts the equilibrium position of a reaction in a favorable direction
(C) The reaction in which products also act as catalysis are called auto-catalyzed reactions
(D) The catalyst does not initiate a chemical reaction

41. : Which statement is NOT related to collision theory?
(A) Molecules must collide with each other to do a chemical reaction
(B) Collision theory is applicable to liquids only
(C) Molecules must have proper orientation
(D) Molecules must possess a minimum amount of energy