MCQ of Chemical Kinetics | Chapter 4 | Chemistry | Class X12 | CBSE |


MCQ of Chemical Kinetics | Multiple Choice Questions of Chemical Kinetics

MCQ of Chemical Kinetics

Question 1: How does concentration of reaction change with time for a chemical reaction ?

  1. Increases 
  2. Remain Unchanged
  3. Decreases
  4. Becomes twice

Answer: C (Decreases)

Question 2: The rate constant of a reaction is 3 x 10 2 min -1 . What is the order of the reaction?

  1. First
  2. Second
  3. Third
  4. Zero

Answer: A (First)

Question 3: For a reaction R→P, half life (t 1/2) is observed to be independent of the initial concentration of reactants. What is the order of reaction?

  1. Zero
  2. First
  3. Second
  4. None of these 

Answer: B (First) 

Question 4: A reaction in which reactants are converted into products follows second order kinetics. If concentration of R is increases by four times, what will be the increase in rate of formation of P?

  1. 9 times
  2. 4 times
  3. 16 times
  4. 8 times

Answer: C (16 times) 

Question 5: The order of reaction is decided by 

  1. Temperature
  2. Mechanism of reaction as well as relative concentration of reactants
  3. Molecularity
  4. Pressure 

Answer: B (Mechanism of reaction as well as relative concentration of reactants)

Question 6: Which of the following for order of reaction is not correct?

  1. Order can be determined experimentally
  2. Order of reaction is equal to the sum of powers of concentration term in rate law expression.
  3. Order cannot be fractional
  4. Order is not affected by stoichiometric coefficient of the reactants. 

Answer: C (Order cannot be fractional)

Question 7: A reaction is of second order with respect to a reactant. How is the rate of reaction affected, if the concentration of reaction is reduced to half?

  1. 4 times
  2. 1/4 times
  3. 16 times
  4. Remain unchanged 

Answer: B (1/4 times) 

Question 8: For a chemical reaction , R→P, the variation in concentration of R with time pot is given as below, predict the order of reaction? 

  1. Zero order
  2. First order
  3. Second order
  4. Insufficient information

Answer: A  (zero order) 

Question 9: For a reaction A+ B → P, the rate law is given by , r = k[A]1/2 [B]2 . What is the order of this reaction?

  1. 1/2 
  2. 2
  3. 5/2
  4. 3/2 

Answer: C  (5/2)

Question 9: The overall rate of reaction is governed by 

  1. The rate of fastest intermediate step
  2. The sum of the rates of all intermediate steps
  3. The average of the rates of all the intermediate steps
  4. The rate of slowest intermediate step

Answer: D (The rate of slowest intermediate step)



Question 10: Under what conditions a bimolecular reaction may be of first order?

  1. When both reactants have same concentration.
  2. When one of the reacting species is in large excess.
  3. When the reaction is at equilibrium.
  4. When the activation energy of reaction is less. 

Answer: B (When one of the reacting species is in large excess. ) 

Question 11: In pseudo unimolecular reactions,

  1. Both the reactants are present in low concentration
  2. Both the reactants are present in same concentration
  3. One of the reactant is present in excess
  4. One of the reactant is non reactive 

Answer: C (one of the reactant is present in excess)

Question 12: When a catalyst is used in an equilibrium process

  1. It increases the rate of forward reaction 
  2. It decreases the rate of backward direction 
  3. It decreases activation energy of both forward and backward direction
  4. It fastens the attainment of equilibrium by lowering activation energy. 

Answer: D  (It fastens the attainment of equilibrium by lowering activation energy.)

Question 13: Half life period of a first order reaction is 10 min. What percentage of the reaction will be completed in 100 min?

  1. 25%
  2. 50%
  3. 99.9%
  4. 75% 

Answer: C  (99.9%)

Question 14: Threshold energy is equal to 

  1. Activation energy
  2. Activation energy – energy of molecules
  3. Activation energy + energy of molecules
  4. None of these 

Answer: C  (Activation energy + energy of molecules)

Question 15: The unit of rate and rate constant are same for a 

  1. Zero order reaction
  2. First order reaction
  3. Second order reaction
  4. Third order reaction 

Answer: A (Zero order reaction) 

Question 16: The number of molecules of the reactants taking place in a single step of the reaction is indicative of 

  1. Order of reaction 
  2. Molecularity of reaction
  3. Fast step of the mechanism of reaction
  4. Half life of the reaction 

Answer: B (molecularity of reaction) 

Question 17: What will be the rate equation for the reaction 2 X + Y → Z, if the order of the reaction is zero?

  1. Rate = k[X][Y]     
  2. Rate = k   
  3. Rate = k[X]0[Y] 
  4. Rate =k[X][Y]0   

Answer: B (Rate = k)

Question 18: For a reaction X → Y, the rate of reaction becomes twenty seven times when the concentration of X is increases three times. What is order of the reaction?

  1. 2
  2. 1
  3. 3
  4. 0

Answer: C (3)

Question 19: The rate constant of a reaction depends upon

  1. Temperature of the reaction
  2. Extent of the reaction
  3. Initial concentration of the reactants
  4. The time of completion of reaction 

Answer: A (Temperature of the reaction)

Question 20: The rate of a chemical reaction doubles for every 10ºC rise of temperature. If the temperature is raised by 50ºC , the rate of the reaction increases by about:

  1. 24 times
  2. 32 times
  3. 64 times
  4. 10 times

Answer: B (32 times )

Question 21: In the presence of a catalyst, the heat evolved or absorbed during the reaction….

  1. Increases
  2. Decreases
  3. Remains unchanged
  4. May increase or decrease

Answer: C (Remains unchanged) 

Question 22: The increase in concentration of the reactants lead to change in 

  1. ΔH 
  2. Collision frequency
  3. Activation energy
  4. Equilibrium constant

Answer: B (Collision frequency) 

Question 23: For an endothermic reaction, ΔH represents the enthalpy of reaction. The minimum amount of activation energy will be

  1. Less than zero
  2. Equal to ΔH
  3. Less than ΔH
  4. More than ΔH 

Answer: D (More than ΔH) 

Question 24: The chemical reaction in which reactant require high amount of activation energy are generally

  1. Slow
  2. Fast
  3. Instantaneous
  4. None of these 

Answer: A  (Slow) 

Question 25: Collision theory is applicable to 

  1. First order reactions
  2. Zero order reactions
  3. Bimolecular reactions
  4. Intramolecular reactions 

Answer: C (Bimolecular reactions)


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