JEE Chemistry Chemical Kinetics MCQs Set B

Question:

• a) the energy below which colliding molecules will not react
• b) the energy below which all the colliding molecules will react
• c) the fraction of molecules with energy greater than the activation energy of the reaction
• d) the total energy of the reacting molecules at a temperature, T

Answer: the energy below which colliding molecules will not react

Question: The minimum energy required for the reacting molecules to undergo reaction is

• a) activation energy
• b) kinetic energy
• c) potential energy
• d) thermal energy

Answer: activation energy

Question: The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by 10°C is

• a) collision frequency increases
• b) the fraction of the molecule having energy equal to threshold energy or more increases
• c) activation energy decreases
• d) the value of threshold energy increases

Answer: collision frequency increases

Question: The slope in Arrhenius plot, is equal to

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The activation energy for a reaction is 9.0 kcal/mol. The increase in the rate constant when its temperature isincreased from 298K to 308K is

• a) 63%
• b) 50%
• c) 10%
• d) 100%

Answer: 63%

Question: In a reversible reaction the energy of activation of the forward reaction is 50 kcal. The energy of activation for the reverse reaction will be

• a) either greater than or less than 50 kcal
• b) 50 kcal
• c) > 50 kcal
• d) < 50 kcal

Answer: either greater than or less than 50 kcal

Question: A catalyst

• a) increases the rate of reaction by providing an alternative pathway via an intermediate with lower activation energy
• b) increases the rate of reaction by decreasing activation energy of the forward reaction
• c)

  

• d)

  

Answer: increases the rate of reaction by providing an alternative pathway via an intermediate with lower activation energy

Question: Which of the following statements best describes how a catalyst works?

• a) A catalyst lowers the activation energy for the reaction by providing a different reaction mechanism
• b) A catalyst destroys some of the reactants, which lowers the concentration of the reactants.
• c) A catalyst decreases the temperature of the reaction which leads to a faster rate
• d) A catalyst changes the potential energies of the reactants and products

Answer: A catalyst lowers the activation energy for the reaction by providing a different reaction mechanism

Question: In terms of the ‘Collision Theory of Chemical Kinetics’, the rate of a chemical reaction is proportional to

• a) the number of collisions per second
• b) the number of products molecules
• c) the change in temperature per second
• d) the change in free energy per second

Answer: the number of collisions per second

Question: According to collision theory, which of the following is NOT a true statement concerning a catalyst?

• a) A catalyst changes the temperature of reaction
• b) The mechanism of a reaction will change when a catalyst is added
• c) A catalyst provides a different activation energy for a reaction
• d) A catalyst changes the speed of a reaction, but not the equilibrium constant

Answer: A catalyst changes the temperature of reaction

Question: Which of the following influences the rate of a chemical reaction performed in solution?

• a) All of the above influence the rate
• b) Presence of a catalyst
• c) Activation energy
• d) Temperature

Answer: All of the above influence the rate

Question: How can be activation energy for a reaction be determined graphically?

• a)

  

• b)

  

• c) Both
• d) None of these

Answer:

Question: The Arrhenius equation expressing the effect of temperature on the rate constant of the reaction is

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: In Arrhenius plot, intercept is equal to

• a) ln A
• b) log₁₀a
• c) ln k
• d) None of these

Answer: ln A

Question: A chemical reaction was carried out at 300 K and 280 K. The rate constants were found to be k₁ and k₂ respectively. then

• a) k₂ = 0.25 k₁
• b) k₁ = 4k₁
• c) k₂ = 2k₁
• d) None of these

Answer: k₂ = 0.25 k₁

Question: For a first order reaction, the plot of log K against 1/T is a straight line. The slope of the line is equal to

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Collision theory is applicable to

• a) bimolecular reactions
• b) first order reactions
• c) zero order reactions
• d) intra-molecular reactions

Answer: bimolecular reactions

Question: According to the collision theory of reaction rates, the rate of reaction increases with temperature due to

• a) greater number of collision
• b) higher velocity of reacting molecules
• c) greater number of molecules having the activation energy
• d) decrease in the activation energy

Answer: greater number of collision

Question: Which of the following has been used to explain the subject of chemical kinetics

• a) All of these
• b) Arrhenius equation
• c) The activated complex theory
• d) Collision theory of bimolecular reactions

Answer: All of these

Question: A catalyst increases rate of reaction by

• a) decreasing activation energy
• b) increasing activation energy
• c) decreasing internal energy
• d) decreasing enthalpy

Answer:  decreasing activation energy

Question: Activation energy of the reaction is

• a) minimum amount of energy needed to overcome the potential barrier
• b) the energy evolved when activated complex is formed
• c) the energy released during the reaction
• d) the energy needed to form one mole of the product

Answer: minimum amount of energy needed to overcome the potential barrier

Question: In a reaction, the threshold energy is equal to

• a) activation energy + normal energy of reactants
• b) activation energy - normal energy of reactants
• c) normal energy of reactants - activation energy
• d) average kinetic energy of molecules of reactants

Answer: activation energy + normal energy of reactants

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a) 20
• b) 120
• c) 300
• d) 280

Answer: 20

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: In most cases, for a rise of 10K temperature the rate constant is doubled to tribled. This is due to the reason that

• a) fraction of molecules possessing threshold energy increases by a factor of 2 to 3
• b) collision frequency increases by a factor of 2 to 3
• c) Activation energy is lowered by a factor of 2 to 3.
• d) none of these

Answer: fraction of molecules possessing threshold energy increases by a factor of 2 to 3

Question:

• a) Activation energy of forward reaction is E₁ + E₂ and product is less stable than reactant
• b) Activation energy of forward reaction is E₁ + E₂ and product is more stable than reactant.
• c) Activation energy of backward reaction is E₁ and product is more stable than reactant.
• d) None of these

Answer: Activation energy of forward reaction is E₁ + E₂ and product is less stable than reactant

Question: Activation energy of a chemical reaction can be determined by ___________

• a) determining the rate constants at two temperatures.
• b) determining the rate constant at standard temperature.
• c) determining probability of collision
• d) using catalyst

Answer: determining the rate constants at two temperatures.

Question: According to which theory activation energy and proper orientation of the molecules together determine the criteria for an effective collision ?

• a) Collision theory
• b) Activated complex theory
• c) Arrhenius theory
• d) None of these

Answer: Collision theory

Question:

• a) TFTF
• b) TFFT
• c) TTTT
• d) FTFT

Answer: TFTF

Question:

• a) (i) and (iii)
• b) (i) and (ii)
• c) (ii) and (iii)
• d) (i) only

Answer: (i) and (iii)

Question: Study the following graphs and choose the correct option

(i) in fig. a, A represents average rate and B represents instantaneous rate

(ii) in fig. b, D represents average rate and C represents instantaneous rate

(iii) fig. a, A represents instantaneous rate and B represents average rate

(iv) fig. b, C represents average rate and D represents instantaneous rate

• a) (i) and (ii) are correct
• b) (i) and (iv) are correct
• c) (ii) and (iv) are correct
• d) (ii) and (iii) are correct

Answer: (i) and (ii) are correct

Question: Choose correct option based on following statements. Here T stands for true statement and F for false statement

(i) Molecularity is defined as the number of reacting species taking part in a complex reaction,
(ii) Molecularity helps in understanding the mechanism of reaction.
(iii) Reactions with the molecularity three are very rare and slow to proceed.
(iv) Complex reactions involving more than three molecules take place in more than one step.

• a) FTTT
• b) TFTF
• c) TTTF
• d) FTTF

Answer: FTTT

Question: Read the following statements

(i) Order of reaction can be fractional or zero.
(ii) Molecularity of a reaction can be fractional but cannot be zero.
(iii) Slowest step in the complex reaction is considered as a rate determining step.
(iv) Units of rate constant for second order reaction are mol L s–1.
(v) Order is applicable to elementary as well as complex reactions whereas molecularity is applicable only for elementary reactions.
Which of the following is the correct code for the statements above ?

• a) TFTFT
• b) FTTFF
• c) TTFFT
• d) FFFTT

Answer: TFTFT

Question: Consider the following statements with respect of zero order reaction

(i) The rate of the reaction is independent of reactant concentration
(ii) The rate of the reaction is independent of temperature
(iii) The rate constant of the reaction is independent of temperature
(iv) The rate constant of the reaction is independent of reactant concentration

Choose the correct statement(s).

• a) (i) and (iv)only
• b) (i) and (ii) only
• c) (i) only
• d) (iii) and (iv) only

Answer: (i) and (iv)only

Question:

• a) (i) and (iii)
• b) (ii) and (iii)
• c) (i) only
• d) (iii) only

Answer: (i) and (iii)

Question:

• a) (i), (iii) and (iv)
• b) (ii) and (iv)
• c) (i), (ii) and (iii)
• d) (i), (ii) and (iv)

Answer: (i), (iii) and (iv)

Question:

• a) (ii) and (v)
• b) (ii) and (iii)
• c) (i) and (iv)
• d) (iii) and (iv)

Answer: (ii) and (v)

Question: According to collision theory, not all collisions between molecules lead to reaction. Which of the following statements provide reasons for the same ?

(i) The total energy of the two colliding molecules is less than some minimum amount of energy.
(ii) Molecules cannot react with each other unless a catalyst is present.
(iii) Molecules that are improperly oriented during collision will not react.
(iv) Molecules in different states of matter cannot react with each other

• a) (i) and (iii)
• b) (i) and (iv)
• c) (i) and (ii)
• d) (ii) and (iii)

Answer: (i) and (iii)

Question:

• a) FTT
• b) TFT
• c) TTT
• d) FTF

Answer: FTT

Question:

• a) TFFTT
• b) FTFTT
• c) TTTFF
• d) TFFTF

Answer: TFFTT

Question:

• a) (i), (ii) and (iv)
• b) (ii) only
• c) (i) only
• d) (i) and (iv)

Answer: (i), (ii) and (iv)

Question:

• a) A – (q), B – (p), C – (s), D – (r)
• b) A – (r), B – (p), C – (s), D – (q)
• c) A – (q), B – (s), C – (p), D – (r)
• d) A – (p), B – (q), C – (s), D – (r)

Answer: A – (q), B – (p), C – (s), D – (r)

Question:

• a) A – (q), B – (p) ,C – (r)
• b) A – (q), B – (r) ,C – (p)
• c) A – (p), B – (q) ,C – (r)
• d) A – (p), B – (r) ,C – (q)

Answer: A – (q), B – (p) ,C – (r)

Question:

• a) A – (r), B – (p), C – (s), D – (q)
• b) A – (r), B – (s), C – (q), D – (p)
• c) A – (q), B – (s), C – (p), D – (r)
• d) A – (q), B – (p), C – (s), D – (p)

Answer: A – (r), B – (p), C – (s), D – (q)

Question:

• a) A – (r), B – (p), C – (s), D – (q)
• b) A – (p), B – (r), C – (s), D – (q)
• c) A – (r), B – (s), C – (p), D – (q)
• d) A – (q), B – (r), C – (s), D – (p)

Answer: A – (r), B – (p), C – (s), D – (q)

Question:

• a) A – (q), B – (s), C – (p), D – (r)
• b) A – (s), B – (q), C – (p), D – (r)
• c) A – (q), B – (p), C – (s), D – (r)
• d) A – (q), B – (s), C – (p), D – (t)

Answer:  A – (q), B – (s), C – (p), D – (r)

Question:

• a) A – (q), B – (r), C – (s), D – (p)
• b) A – (r), B – (q), C – (s), D – (p)
• c) A – (q), B – (s), C – (r), D – (p)
• d) A – (q), B – (r), C – (p), D – (s)

Answer: A – (q), B – (r), C – (s), D – (p)

Question:

• a) A – (s), B – (r), C – (p), D – (q)
• b) A – (r), B – (s), C – (p), D – (q)
• c) A – (q), B – (r), C – (p), D – (s)
• d) A – (s), B – (r), C – (q), D – (p)

Answer: A – (s), B – (r), C – (p), D – (q)

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a) Y
• b) X
• c) Z
• d) W

Answer: Y

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Rate law for a chemical reaction has to determine experimentally
• b) Rate law for any chemical reaction can be predicted accurately by looking at balanced chemical equation
• c) Either determined experimentally or obtained from balanced chemical reaction, rate law will be same
• d) None of the above is correct

Answer: Rate law for a chemical reaction has to determine experimentally

Question:

Which of the above mechanism(s) can be consistent with the given information about the reaction?

• a) B only
• b) Neither A nor B
• c) A and B both
• d) A only

Answer: B only

Question:

• a) 3/2
• b) 1
• c) 0
• d) 2

Answer: 3/2

Question:

• a) 2, 1, 0
• b) 3, 2, 1
• c) 3, 2, 0
• d) 2, 2, 0

Answer: 2, 1, 0

Question:

• a)

  

• b)

  

• c) Both
• d) None of these

Answer:

Question:

• a) 3
• b) 1
• c) 0
• d) 2

Answer: 3

Question:

• a) a first order reaction
• b) a second order reaction
• c) independent of the initial concentration of the salt
• d) a zero order reaction

Answer: a first order reaction

Question:

• a) Increasing the concentration of (CH₃₎₃COH
• b) Increasing the concentration of HCl
• c) Decreasing the concentration of HCl
• d) None of these

Answer: Increasing the concentration of (CH₃₎₃COH

Question:

• a) (ii) and (iii)
• b) (i), (ii) and (iii)
• c) (i) and (ii)
• d) (iii) only

Answer: (ii) and (iii)

Question: The decomposition of ammonia on tungsten surface at 500 K follows zero order kinetics. The half-life period of this reaction is 45 minutes when the initial pressure is 4 bar. The half-life period (minutes) of the reaction when the initial pressure is 16 bar at the same temperature is

• a) 180
• b) 60
• c) 120
• d) 240

Answer: 180

Question: A substance 'A' decomposes by a first order reaction starting initially with [A] = 2.00 M and after 200 min, [A] becomes 0.15 M. For this reaction t_1/2 is

• a) 53.72 min
• b) 50.49 min
• c) 46.45 min
• d) 48.45 min

Answer: 53.72 min

Question: If half-life of a substance is 5 yrs, then the total amount of substance left after 15 years, when initial amount is 64 grams is

• a) 8 grams
• b) 2 grams
• c) 16 grams
• d) 32 grams

Answer: 8 grams

Question: In a 1st order reaction, reactant concentration C varies with time t as

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a) 40 minutes
• b) 120 minutes
• c) 20 minutes
• d) 80 minutes

Answer: 40 minutes

Question: Which of the following graph(s) is/are correct for a zero order reaction?

• a) (i) and (iv)
• b) (i), (ii) and (iii)
• c) (ii) and (iii)
• d) (ii), (iii) and (iv)

Answer: (i) and (iv)

Question: The integrated rate equations can be determined for

• a) Both
• b) zero order reactions
• c) first order reactions
• d) None of these

Answer: Both

Question: In a zero-order reaction for every 10° rise of temperature, the rate is doubled. If the temperature is increased from 10°C to 100°C, the rate of the reaction will become

• a) 512 times
• b) 128 times
• c) 256 times
• d) 64 times

Answer: 512 times

Question:

• a) 1.0 × 10⁶ s^–1 and 38.3 kJ mol^–1
• b) 1.0 × 10⁶ s^–1 and 16.6 kJ mol^–1
• c) 6.0 s^–1 and 16.6 kJ mol^–1
• d) None of these

Answer: 1.0 × 10⁶ s^–1 and 38.3 kJ mol^–1

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: A graph plotted between log k vs 1/T for calculating activation energy is shown by

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 6.0 × 10¹⁴ s^–1
• b) 3.6 × 10³⁰ s^–1
• c) Infinity
• d) None of these

Answer:  6.0 × 10¹⁴ s^–1

Question: Collision theory is used to explain how chemical species undergo a reaction. Using this theory and the kinetic molecular model, which of the following does NOT influence the rate of a chemcial reaction?

• a) All of the above influence the rate
• b) The velocity of the reactants at the point of collision
• c) The geometry or orientation of the collision
• d) The temperature of the system

Answer:  All of the above influence the rate

Question:

• a) 100%
• b) 20%
• c) 60%
• d) 50%

Answer: 100%

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Which of the following statements is not correct for the catalyst?

• a)

  

• b) It catalyses the forward and backward reaction to the same extent
• c) It is a substance that does not change the equilibrium constant of a reaction
• d) It provides an alternate mechanism by reducing activation energy between reactants and products.

Answer:

Question: During decomposition of an activated complex.

(i) energy is always released
(ii) energy is always absorbed
(iii) energy does not change
(iv) reactants may be formed

• a) (i) and (iv)
• b) (i), (ii) and (iii)
• c) (ii) and (iii)
• d) (ii), (iii) and (iv)

Answer: (i) and (iv)

Question: Which of the following statements is incorrect ?

• a) Peak of the energy distribution curve corresponds to the most probable potential energy
• b) Peak of the energy distribution curve corresponds to the most probable kinectic energy
• c) When the temperature is raised maximum of energy distribution curve moves to higher energy value and broadens out
• d) Energy is always released when activated complex decomposes to form products

Answer: Peak of the energy distribution curve corresponds to the most probable potential energy