Chemical Kinetics MCQs 2026

Which of the following is an example of a very slow reaction under normal conditions

1. A Explosion of gunpowder ✓
2. B Neutralization reaction ✓
3. C Rusting of iron ✓
4. D Precipitation of silver chloride ✓

Which of the following is an example of a very fast reaction

1. A Rusting of iron ✓
2. B Souring of milk ✓
3. C Neutralization of a strong acid with a strong base ✓
4. D Fermentation of sugar ✓

For a zero-order reaction, a plot of concentration [A] versus time gives a

1. A Curve ✓
2. B Straight line with negative slope ✓
3. C Straight line with positive slope ✓
4. D Exponential curve ✓

The half-life of a second-order reaction is

1. A Independent of initial concentration ✓
2. B Equal to that of a zero-order reaction ✓
3. C Inversely proportional to the initial concentration ✓
4. D Directly proportional to the square of initial concentration ✓

A plot of ln[A] versus time for a first-order reaction gives a

1. A Curve with increasing slope ✓
2. B Parabola ✓
3. C Straight line with negative slope ✓
4. D Straight line with positive slope ✓

The integrated rate law for a first-order reaction is given by

1. A [A] = [A]0 − kt ✓
2. B 1/[A] = 1/[A]0 + kt ✓
3. C ln[A] = ln[A]0 − kt ✓
4. D [A] = k[A]0t ✓

Pseudo first-order reactions appear to follow first-order kinetics because

1. A All reactants are in equal concentration ✓
2. B One reactant is present in large excess so its concentration remains effectively constant ✓
3. C The reaction has no rate-determining step ✓
4. D The catalyst controls the entire rate ✓

Which of the following would decrease the rate of a reaction between a solid and a gas

1. A Decreasing the surface area of the solid ✓
2. B Increasing the temperature ✓
3. C Increasing the concentration of the gas ✓
4. D Adding a suitable catalyst ✓

For a chain reaction such as the combustion of hydrocarbons, the steps typically include initiation, propagation, and

1. A Neutralization ✓
2. B Hydrolysis ✓
3. C Termination ✓
4. D Sublimation ✓

Which of the following statements about catalysts is correct

1. A A catalyst does not alter the equilibrium position of a reversible reaction ✓
2. B A catalyst changes the value of the equilibrium constant ✓
3. C A catalyst is consumed during the reaction ✓
4. D A catalyst only works on exothermic reactions ✓

Enzyme-catalyzed reaction rates are strongly affected by

1. A Only the color of the substrate ✓
2. B Atomic mass of the enzyme ✓
3. C The container's shape ✓
4. D Temperature and pH ✓

The pre-exponential (frequency) factor, A, in the Arrhenius equation, is related to the

1. A Activation energy exclusively ✓
2. B Gas constant only ✓
3. C Concentration of the catalyst ✓
4. D Frequency of collisions and their proper orientation ✓

Which of the following best describes the rate of reaction as time progresses in a typical reaction (with reactants being consumed)

1. A It generally decreases as reactant concentration decreases ✓
2. B It generally increases over time ✓
3. C It remains constant throughout ✓
4. D It becomes negative ✓

A negative catalyst, or inhibitor, works by

1. A Lowering the activation energy ✓
2. B Increasing the rate of reaction ✓
3. C Shifting equilibrium towards products ✓
4. D Slowing down the rate of a reaction ✓

When temperature increases, the Maxwell-Boltzmann distribution curve shifts to show

1. A Fewer high-energy molecules ✓
2. B No change in molecular energy distribution ✓
3. C All molecules having identical energy ✓
4. D A greater fraction of molecules with energy above the activation energy ✓

The Maxwell-Boltzmann distribution curve shows the distribution of

1. A Reaction rates over time ✓
2. B Molecular kinetic energies in a sample of gas ✓
3. C Concentration of reactants over time ✓
4. D Activation energies of different reactions ✓

Autocatalysis refers to a reaction in which

1. A No catalyst is involved at all ✓
2. B An external catalyst must be added continuously ✓
3. C One of the products formed acts as a catalyst for the reaction ✓
4. D The reactants catalyze each other's decomposition only ✓

An example of heterogeneous catalysis is

1. A Use of solid iron catalyst in the Haber process (gaseous reactants) ✓
2. B Acid-catalyzed ester hydrolysis in solution ✓
3. C Enzyme action in the bloodstream ✓
4. D Homogeneous gas-phase catalysis only ✓

Which type of catalyst exists in a different physical phase from the reactants, such as a solid catalyst for gaseous reactants

1. A Homogeneous catalyst ✓
2. B Heterogeneous catalyst ✓
3. C Biological catalyst only ✓
4. D Autocatalyst only ✓

Which type of catalyst exists in the same physical phase as the reactants

1. A Heterogeneous catalyst ✓
2. B Homogeneous catalyst ✓
3. C Enzyme catalyst only ✓
4. D Solid catalyst only ✓

The rate of reaction is generally measured experimentally by monitoring the change in

1. A Concentration of a reactant or product over time ✓
2. B Total mass of the system ✓
3. C Color of the container ✓
4. D Temperature of the room ✓

According to the Arrhenius equation, increasing temperature increases the rate constant primarily because it increases the

1. A Activation energy of the reaction ✓
2. B Fraction of molecules with energy equal to or greater than the activation energy ✓
3. C Concentration of reactants ✓
4. D Volume of the container ✓

A photochemical reaction is one that is initiated or driven by

1. A Heat energy ✓
2. B Light energy ✓
3. C Electrical energy ✓
4. D Mechanical energy ✓

Enzymes act as biological catalysts by

1. A Increasing the temperature of the reaction ✓
2. B Being permanently consumed in the reaction ✓
3. C Lowering the activation energy of biochemical reactions ✓
4. D Shifting the equilibrium constant ✓

For a first-order reaction, doubling the concentration of the reactant will increase the rate by a factor of

1. A 1 ✓
2. B 2 ✓
3. C 4 ✓
4. D 0.5 ✓

For a second-order reaction, doubling the concentration of the reactant will increase the rate by a factor of

1. A 2 ✓
2. B 4 ✓
3. C 8 ✓
4. D 1 ✓

The units of a rate constant depend on the

1. A Overall order of the reaction ✓
2. B Temperature only ✓
3. C Volume of the container ✓
4. D Nature of the catalyst ✓

A reaction intermediate, unlike a transition state, is

1. A Never formed during a reaction ✓
2. B The same as activation energy ✓
3. C Always the final product ✓
4. D A species that is formed and then consumed during the reaction mechanism, with a finite lifetime ✓

Which of the following would increase the frequency of effective collisions between reactant molecules

1. A Increasing temperature ✓
2. B Decreasing concentration ✓
3. C Decreasing surface area ✓
4. D Removing the catalyst ✓

A transition state (activated complex) is

1. A A high-energy, unstable, transient arrangement of atoms during a reaction ✓
2. B A stable intermediate that can be isolated ✓
3. C The same as a catalyst ✓
4. D The final product of a reaction ✓

The rate-determining step of a multi-step reaction mechanism is the

1. A Fastest step ✓
2. B First step always ✓
3. C Last step always ✓
4. D Slowest step, which controls the overall rate ✓

Radioactive decay follows ___ order kinetics

1. A First ✓
2. B Second ✓
3. C Zero ✓
4. D Third ✓

The half-life of a first-order reaction is

1. A Independent of the initial concentration of reactant ✓
2. B Directly proportional to initial concentration ✓
3. C Inversely proportional to initial concentration ✓
4. D Equal to zero ✓

The Arrhenius equation relates the rate constant k to the

1. A Concentration of products ✓
2. B Order of reaction only ✓
3. C Equilibrium constant ✓
4. D Temperature and activation energy ✓

The rate constant, k, of a reaction depends on

1. A Concentration of reactants only ✓
2. B Volume of container ✓
3. C Temperature (and the presence of a catalyst) ✓
4. D Time elapsed ✓

The overall order of a reaction is the sum of the

1. A Coefficients in the balanced equation ✓
2. B Molar masses of reactants ✓
3. C Activation energies ✓
4. D Exponents of concentration terms in the rate law ✓

For a zero-order reaction, the rate is

1. A Independent of the concentration of reactant ✓
2. B Directly proportional to concentration ✓
3. C Proportional to the square of concentration ✓
4. D Always equal to zero ✓

Chemical kinetics is the study of the

1. A Position of equilibrium ✓
2. B Heat changes in reactions ✓
3. C Rate and mechanism of chemical reactions ✓
4. D Structure of molecules ✓

The rate of a chemical reaction is generally expressed as the change in concentration of reactant or product per unit

1. A Volume ✓
2. B Time ✓
3. C Mass ✓
4. D Pressure ✓

Which of the following factors does NOT typically affect the rate of a reaction

1. A Temperature ✓
2. B Concentration of reactants ✓
3. C Presence of a catalyst ✓
4. D Color of the container ✓

Increasing the temperature of a reaction generally ___ its rate

1. A Decreases ✓
2. B Increases ✓
3. C Has no effect on ✓
4. D Reverses ✓