Chemical Kinetics questions will always be relevant, be it for AIIMS, NEET or JEE exam. These types of questions are based on an understanding of mathematical concepts like kinetics and rate of reaction. The first order reaction is common in all the three exams.

Chemical Kinetics Questions (Pseudo First Order Reaction)

1. Acid hydrolysis of esters such as CH₃COOC₂H₅ in aqueous solution is an example of a pseudo first-order reaction.

a) True

b) False

Answer: True

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?

a) s^-1

b) mol L^-1s^-1

c) mol^-1 L s^-1

d) mol^-2 L² s^-1

Answer: s^-1

9. Reactions whose molecularity is one but order is more than one are known as pseudo first-order reactions.

a) True

b) False

Answer: False

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

Categories: Chemical Kinetics