This Chemical Kinetics Questions and Answers PDF is useful for the students of NEET, AIIMS, JEE, and other entrance examinations. This Chemical Kinetics Questions And Answers PDF contains more than 100 MCQs on various concepts of chemical kinetics which are asked in examinations like NEET, JEE and AIIMS.
Chemical Kinetics Questions And Answers PDF
These Chemical Kinetics Questions And Answers PDF contains the following topics:
Collision Theory of Chemical Reactions
1. Who put forward the collision theory of chemical reactions?
a) Trautz and Lewis
b) Luigi Galvani
c) Henry Cavendish
d) Alessandro Volta
Answer: Trautz and Lewis
2. The proper orientation of reactant molecules leads to bond formation.
3. Which of the following is a drawback of collision theory?
a) Proper orientation
b) High activation energy
c) Hard spheres
d) Have energy equal to or greater than the threshold energy
Answer: Hard spheres
4. What is the term used to refer to the number of collisions per unit volume of the reaction mixture?
a) Collision force
b) Collision frequency
c) Collision energy
d) Collision time period
Answer: Collision frequency
5. What is the rate of reaction for a bimolecular elementary reaction?
a) ZAB e-Ea/RT
b) ZAB eEa/RT
c) – ZAB e-Ea/RT
d) – ZAB eEa/RT
Answer: ZAB e-Ea/RT
6. In a chemical reaction, if the reactant requires a high amount of activation energy, then what is the behaviour of the reaction?
d) Doesn’t depend on activation energy
7. What are the factors that determine an effective collision?
a) Translational collision and energy of activation
b) Threshold energy and proper orientation
c) Proper orientation and steric bulk of the molecule
d) Collision frequency, threshold energy and proper orientation
Answer: Collision frequency, threshold energy and proper orientation
8. When a catalyst is involved in the collision between the reactant molecules, more energy is required.
9. Which of the following explains the increase in the reaction rate by a catalyst?
a) Catalyst decreases the rate of backward reaction so that rate of forward reaction increases
b) Catalyst provides extra energy to reacting molecules so that they produce effective collisions
c) Catalyst provides an alternative path of lower activation energy to the reactants
d) Catalyst increases the number of collisions between the reacting molecules.
Answer: Catalyst provides an alternative path of lower activation energy to the reactants
10. Effective collisions are those in which molecules must acquire the energy of activation.
Factors Influencing Rate of a Reaction
1. What happens to the rate of the reaction on increasing its temperature?
a) Rate of reaction increases
b) Rate of reaction decreases
c) Rate of reaction fluctuates between its maxima and minima
d) Rate of reaction is independent of temperature
Answer: Rate of reaction increases
2. Which of the following laws state that the rate of a chemical reaction is directly proportional to the concentration of reactants?
a) Henry’s law
b) Law of conservation of mass
c) Law of mass action
d) Dalton’s law
Answer: Law of mass action
3. A catalyst only increases the rate of the reaction in the forward direction.
4. What happens to the value of ΔG of a reaction when a catalyst is added to it?
a) It increases
b) It decreases
c) It remains unchanged
d) It is undefined on adding a catalyst
Answer: It remains unchanged
5. What is the change in the rate of a second order reaction when the concentration of the reactant is increased by 2 times its initial value?
a) It doubles
b) No change
c) It quadruples
d) It triples
Answer: It quadruples
6. When the two reactants are in the same phase, then which common phase will ensure that the products are formed at the fastest pace?
d) The rate of a reaction is independent of the phase of the reactants
7. Which of the following is a factor that automobile engines use to increase the rate of its internal reactions?
a) Concentration of fuel
b) Viscosity of the fuel
c) Surface area of the reactants
d) Nature of the fuel
Answer: Surface area of the reactants
8. Rate of a reaction depends on the ΔH of the reaction.
9. Which of the following is not a direct factor affecting the rate of a reaction?
b) Presence of catalyst
c) Order of reaction
10. Which of the following will lead to an increase in the rate of the reaction?
a) Decrease in temperature
b) Decreasing concentration of reactants
c) Addition of catalyst
d) Addition of inhibitor
Answer: Addition of catalyst
Integrated Rate Equations
1. What is the integrated rate equation for a first order reaction?
a) [A] = [A]0e-kt
b) [A] = [A]0/e-kt
c) [A] = [A]0e-t
d) [A] = [A]0e-k
Answer: [A] = [A]0e-kt
2. For a certain reaction the values of Arrhenius factor and Activation energy are 4 x 1013 collision/sec and 98.6KJ/mol at 303K. Calculate the rate constant if reaction is 1st order?( R=8.341mol-1K-1)
a) 6.07 x 10-3
b) 3.02 x 10-5
c) 4.07 x 10-4
d) 7.42 x 10-3
Answer: 4.07 x 10-4
3. The decomposition of N2O5 in CCl4 solution was studied. N2O5 → 2NO2 + 1/2O2. The rate constant of the reaction is 6.2 x 10-4 sec-1. Calculate the rate when the concentration of N2O5 is 1.25 molar.
a) 6.45 x 10-4
b) 7.45 x 10-4
c) 6.75 x 10-4
d) 7.75 x 10-4
Answer: 7.75 x 10-4
4. What is the formula to calculate the time taken for the completion of a zero-order reaction?
a) t100% = [A]0/k
b) t100% = [A]0/2k
c) t100% = 2[A]0/k
d) t100% = [A]0/3k
Answer: t100% = [A]0/k
5. The unit of rate constant of a first-order reaction is s-1.
6. The unit of the rate constant of a zero-order reaction and second-order reaction is same.
7. The half-life of a given reaction is doubled if the initial concentration of the reactant is doubled. What is the order of the reaction?
8. A first-order reaction was 70 percent complete in 20 minutes. What is the rate constant of the reaction?
a) 0.07 min-1
b) 0.06 min-1
c) 0.08 min-1
d) 0.09 min-1
Answer: 60.28 minutes
9. What is the time taken to complete 75 percent of the reaction if the rate of the first-order reaction is 0.023 min-1?
a) 60.28 minutes
b) 69.28 minutes
c) 50.37 minutes
d) 65.97 minutes
Answer: 60.28 minutes
10. For the reaction X → Y + Z, the rate constant is 0.00058 s-1. What percentage of X will be decomposed in 50 minutes?
a) 90.02 percent
b) 82.44 percent
c) 88.82 percent
d) 82.67 percent
Answer: 82.44 percent
11. What is the time required for 75 percent completion of a first-order reaction?
a) 3 × t50
b) 4 × t50
c) 4.5 × t50
d) 2 × t50
Answer: 2 × t50
12. A first-order reaction is 50 percent complete in 30 minutes. Calculate the time taken for completion of 87.5 percent of the reaction.
a) 30 minutes
b) 60 minutes
c) 90 minutes
d) 120 minutes
Answer: 90 minutes
13. The rate constant of a reaction is 0.01s-1, how much time does it take for 2.4 mol L-1 concentration of reactant reduced to 0.3 mol L-1?
14. What time does it take for reactants to reduce to 3/4 of initial concentration if the rate constant is 7.5 x 10-3 s-1?
15. A zero-order reaction is 25% complete in 30seconds. What time does it take for 50% completion?
Pseudo First Order Reaction
1. Acid hydrolysis of esters such as CH3COOC2H5 in aqueous solution is an example of a pseudo first-order reaction.
2. The rate law for inversion of cane sugar is R=k [C12H22O11][H2O]. Find the concentration of sucrose if the rate of the reaction is 0.032 s-1 and rate constant k=0.005.
a) 5.8 M
b) 6 M
c) 6.2 M
d) 6.4 M
Answer: 6.4 M
3. What is the rate law of hydrolysis of CH3COOC2H5 in aqueous solution?
a) R=k [CH3COOC2H5]2
b) R=k [CH3COOC2H5]
c) R=k [CH3COOC2H5] [H2O]
d) R=kk’ [CH3COOC2H5][H2O]
Answer: R=k [CH3COOC2H5]
4. Which of the following is not true for a pseudo first-order reaction?
a) The reaction follows first order kinetics
b) Molecularity of the reaction should be one
c) The reactants such as water are present in excess and are assumed to be constant throughout the reaction
d) Unit of the rate constant is s-1
Answer: Molecularity of the reaction should be one
5. Which of the following is not similar between a first order and pseudo first order reaction?
a) The molecularity is one in both the reactions
b) Both follows first order kinetics
c) The unit of rate constant is s-1
d) The rate of the reaction depends only on one reactant
Answer: The molecularity is one in both the reactions
6. Which of the following is not an example of a pseudo first-order reaction?
a) CH3COOC2H5 + NaOH → CH3COOH + H2O
b) CH3COOC2H5 + H2O → CH3COOH + C2H5OH
c) C2H5COOC2H5 + H2O → C2H5COOH + C2H5OH
d) C12H22O11 + H2O → glucose + fructose
Answer: CH3COOC2H5 + NaOH → CH3COOH + H2O
7. For the reaction C2H5COOC2H5 + H2O → C2H5COOH + C2H5OH, find the concentration of [C2H5COOC2H5] if the rate constant k=0.2 and the rate of the reaction is 0.39 s-1.
a) 2.87 M
b) 2.01 M
c) 1.99 M
d) 1.95 M
Answer: 1.95 M
8. For a pseudo first-order reaction, what is the unit of the rate of the reaction?
b) mol L-1s-1
c) mol-1 L s-1
d) mol-2 L2 s-1
9. Reactions whose molecularity is one but order is more than one are known as pseudo first-order reactions.
10. Which of the following reactions is an example of a pseudo first-order reaction?
a) H2 + Br2 → 2HBr
b) CH3CHO → CH4 + CO
c) C12H22O11 + H2O → glucose + fructose
d) PCl5 → PCl3 + Cl2
Answer: C12H22O11 + H2O → glucose + fructose
Rate of a Chemical Reaction
1. The reaction NO2 + CO → NO + CO2 takes place in two steps. Find the rate law.
2NO2 → NO + NO3 (k1) – slow
NO3 + CO → CO2 + NO2 (k2) – fast
a) R = k1 [NO2]3
b) R = k2 [NO3] [CO]
c) R = k1 [NO2]
d) R = k1 [NO2]2
Answer: R = k1 [NO2]2
2. For the reaction A + H2O → products, find the rate of the reaction when [A] = 0.75 M, k= 0.02.
a) 0.077 s-1
b) 0.085 s-1
c) 0.015 s-1
d) 0.026 s-1
Answer: 0.015 s-1
3. What is the rate law for acid hydrolysis of an ester such as CH3COOC2H5 in aqueous solution?
a) k [CH3COOC2H5]
b) k [CH3COOC2H5] [H2O]
c) k [CH3COOC2H5]2
Answer: k [CH3COOC2H5]
4. What is the concentration of the reactant in a first order reaction when the rate of the reaction is 0.6 s-1 and the rate constant is 0.035?
a) 26.667 M
b) 17.143 M
c) 26.183 M
d) 17.667 M
Answer: 17.143 M
5. How many times will the rate of the elementary reaction 3X + Y → X2Y change if the concentration of the substance X is doubled and that of Y is halved?
a) r2= 4.5r1
b) r2= 5r1
c) r2= 2r1
d) r2= 4r1
Answer: r2= 4r1
6. What is the rate law for the reaction C2H4 + I2 → C2H4I2?
a) R= [C2H4] [I2]3/2
b) R= [C2H4] [I2]3
c) R= [C2H4] [I2]2
d) R= [C2H4] [I2]
Answer: R= [C2H4] [I2]3/2
7. The rate law for the reaction involved in inversion of cane sugar is R=k [C12H22O11] [H2O].
8. For a second-order reaction, what is the unit of the rate of the reaction?
b) mol L-1s-1
c) mol-1 L s-1
d) mol-2 L2 s-1
Answer: mol-1 L s-1
9. The rate constant of a reaction is k=3.28 × 10-4 s-1. Find the order of the reaction.
a) Zero order
b) First order
c) Second order
d) Third order
Answer: First order
10. For a reaction A +B → C, the experimental rate law is found to be R=k[A]1[B]1/2. Find the rate of the reaction when [A] = 0.5 M, [B] = 0.1 M and k=0.03.
a) 4.74 × 10-2 (L/mol)1/2 s-1
b) 5.38 × 10-2 (L/mol)1/2 s-1
c) 5.748 × 10-2 (L/mol)1/2 s-1
d) 4.86 × 10-2 (L/mol)1/2 s-1
Answer: 4.74 × 10-2 (L/mol)1/2 s-1
Temperature Dependence of the Rate of a Reaction
1. What happens to the peak of the curve in the Maxwell-Boltzmann distribution graph if temperature increases?
a) Shifts forward and upward
b) Shifts forward and downward
c) Shifts backward and upward
d) Shifts backward and downward
Answer: Shifts forward and downward
2. Which of the following is the correct Arrhenius equation?
a) k = A eEa/RT
b) k = A eEa/T
c) k = A eEa/R
d) k = A e-Ea/RT
Answer: k = A e-Ea/RT
3. Which of the following represents the Boltzmann factor?
4. What is R in the equation k = Ae-Ea/RT?
a) R = 8.314 J K-1 mol-1
b) R = 3.184 J K-1 mol-1
c) R = 4.318 J K-1 mol-1
d) R = 1.438 J K-1 mol-1
Answer: R = 8.314 J K-1 mol-1
5. The activation energy of a reaction is 50 kJ mol-1 and the value of rate constant at 300 K is 2.5×10-5 sec-1. What is the value of the frequency factor, A?
a) 4228.53 s-1
b) 3829.69 s-1
c) 7596.45 s-1
d) 6565.35 s-1
Answer: 7596.45 s-1
6. What is the value of rate constant k if the value of the activation energy Ea and the frequency factor A are 49 kJ / mol and 9 × 1010 s-1 respectively? (T = 313 K)
a) 6 × 102 s-1
b) 9 × 102 s-1
c) 6 × 10-2 s-1
d) 3 × 102 s-1
Answer: 6 × 102 s-1
7. The rate constant of a reaction is 6 × 10-3 s-1 at 50° and 9 × 10-3 s-1 at 100° C. Calculate the energy of activation of the reaction.
a) 6.123 kJ mol-1
b) 8.124 kJ mol-1
c) 12.357 kJ mol-1
d) 18.256 kJ mol-1
Answer: 6 × 102 s-1
8. The rate of a reaction depends on the temperature.
9. Which of the following is the correct expression for the temperature coefficient (n)?
a) n = Rate constant at T + 10°/Rate constant at T°
b) n = Rate constant at T + 20°/Rate constant at T°
c) n = Rate constant at T + 30°/Rate constant at T°
d)n = Rate constant at T + 40°/Rate constant at T°
Answer: n = Rate constant at T + 10°/Rate constant at T°
10. The rate of reaction increases with a rise in temperature.
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