# Physical Chemistry Questions and Answers – Kinetics of More Complex Multistep Chemical Reactions

This set of Physical Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Kinetics of More Complex Multistep Chemical Reactions”.

1. What is the other name of reaction rate?
a) Density of reaction
b) Speed of reaction
c) Concentration of reaction
d) Temperature of reaction

Explanation: Reaction rate is also known as the speed of reaction which can be defined as how slowly or quickly a reaction takes place.

2. How can a catalyst influence the rate of reaction?
a) By increasing its rate
b) By increasing the surface area
c) By increasing the relative mass
d) By increasing the electromagnetic radiation

Explanation: Rate of reaction can be influenced by so many factors such as temperature, catalyst, etc. A catalyst increases the rate of reaction by providing another way by lowering the activation energy.

3. How temperature influences the rate of reaction?
a) By lowering the activation energy
b) By increasing the surface area
c) By increasing the rate of reaction
d) By increasing the ionic strength

Explanation: Temperature influences the rate of reaction by delivering more energy to the system and increasing the rate of reaction by the collision between the particles.

4. What is the second order reaction law?
a) 1/[A] = 1/[A]0 + 2kt
b) ln[A] = -kt + ln[A]0
c) ln[A] = -kt
d) r = k

Explanation: It depends upon the concentration of the second order reactant, or first two reactants. The integrated second order law is given as 1/[A] = 1/[A]0 + 2kt.

5. What is the law of zero order reaction?
a) ln[A] = -kt
b) [A]t = -kt + [A]0
c) r = kt
d) ln[A] = -kt + ln[A]0

Explanation: r = -d[A]/dt = k if this differential equation is integrated we get the law of second order of reaction that is [A]t = -kt + [A]0 where [A]t represents the concentration at a time and [A]0 represents the initial concentration.

6. What is the half-life of second-order reaction?
a) 1/k[A]0
b) [A]0/2k
c) ln (2)/k
d) r = k[A]

Explanation: The half-life of second-order reaction depends upon the concentration of the second order reactant. Half-life is t1/2 = 1/k[A]0.

7. The rate of reaction decreases with concentration.
a) False
b) True

Explanation: Rate of reaction increases with the concentration as explained by the collision theory. As the concentration of reactant increases, the frequency of collision increases.

8. The transition state is the state with the lowest potential energy.
a) False
b) True

Explanation: Transition state is a state with the highest potential energy along this reaction coordinate. It is often marked with the double dagger symbol.

9. What is an elementary reaction?
a) In which one or more chemical species react to form product in a single step
b) In which one or more chemical species react to form product in double steps
c) In which reaction does not occur without catalyst
d) In which reaction occur without catalyst

Explanation: It is a single step chemical reaction in which chemical reactants react directly to form products. In a unimolecular reaction, a molecule isomerizes to form a product.

10. What is molecularity of a reaction?
a) In which molecule react exactly as stoichiometric equation
b) In which one or more chemical species react to form product in double steps
c) Number of molecules that participate in rate determining step
d) In which one or more chemical species react to form product in a single step

Explanation: Molecularity of a reaction is the number of molecules that participate in the rate-determining step. It is a process in which two reacting species combine in a transition state.

Sanfoundry Global Education & Learning Series – Physical Chemistry.

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