Free Reaction Kinetics MCQs with Answers
573 Reaction Kinetics MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Reaction kinetics relates reaction rate to concentration, temperature, surface area and catalysts. Questions cover rate laws, reaction order, rate constants, activation energy and the activated complex, including how a catalyst lowers the activation energy without changing the overall energy change or equilibrium position.
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573 questions · page 3 of 29
- A. I and II quadrant
- B. II and III quadrant
- C. III and IV quadrant
- D. II and IV quadrant
Explanation: The Arrhenius equation in logarithmic form is log k = log A - Ea/(2.303R) x 1/T, so a plot of log k against 1/T has a negative slope.
Correct answer: II and IV quadrant- A. Time
- B. Concentration of the reactant
- C. Temperature
- D. Concentration of the product
Explanation: For a given reaction, the first-order rate constant remains independent of reactant concentration and changes mainly with temperature…
Correct answer: Temperature- A. s-1
- B. mol dm-3 s-1
- C. mol-1 dm3 s-1
- D. mol-2 dm6 s-1
Explanation: For a zero-order reaction, rate = k, so k has the same dimensions as rate: concentration per time. Therefore its unit is mol dm^-3 s^-1.
Correct answer: mol dm-3 s-1- A. First order reaction
- B. Second order reaction
- C. Zero order reaction
- D. Third order reaction
Explanation: For a zero-order reaction, rate = k, so the numerical value and units of k are the same as those of the reaction rate, commonly mol dm-3…
Correct answer: Zero order reaction- A. Separating factors
- B. decreasing factors
- C. Colouring factors
- D. retardation factors
Explanation: The distribution coefficient is the ratio of a solute's concentration in two phases at equilibrium, and differences in this ratio allow…
Correct answer: Separating factors- A. Catalyst
- B. Intermediate
- C. inhibitor
- D. activated complex
Explanation: An intermediate is formed in one elementary step and consumed in a later step, so it does not appear in the overall reaction equation.
Correct answer: Intermediate- A. Greater will be dx/dt
- B. Lesser will be dx/dt
- C. dx/dt will be moderate
- D. any of above
Explanation: For a reaction with a positive order, increasing reactant concentration increases the frequency of effective collisions, so the rate dx/dt…
Correct answer: Greater will be dx/dt- A. Concentration of reactant does not change
- B. Concentration of product increases
- C. Concentration of reactant decreases
- D. Concentration of reactant increases
Explanation: A negative sign before a reactant concentration change shows that the reactant is being consumed, so its concentration decreases with…
Correct answer: Concentration of reactant decreases- A. Fast step
- B. Slowest step
- C. All steps
- D. Molecularity of the reaction
Explanation: In a multistep mechanism, the slowest elementary step has the greatest resistance and limits how quickly the overall reaction can proceed.
Correct answer: Slowest step- A. Moles dm-3 sec-1
- B. Moles dm-3
- C. Moles sec-1
- D. Mol-1 dm3 sec-1
Explanation: Reaction rate is the change in concentration per unit time, so its usual unit is moles dm-3 sec-1.
Correct answer: Moles dm-3 sec-1- A. rate of forward reaction
- B. rate of backward reaction
- C. rate constant
- D. rate co-efficient
Explanation: The conversion of reactants into products per unit time is the rate of the forward reaction, expressed through the decrease in reactant…
Correct answer: rate of forward reaction- A. very slow
- B. very fast
- C. slow
- D. no regular character present
Explanation: Most organic reactions are relatively slow because covalent bonds are strong and many reactions require significant activation energy or…
Correct answer: slow- A. Average Kinetic Energy of the molecules
- B. Potential Energy of the molecules
- C. Free Energy of the molecules
- D. Activation Energy of the molecules
Explanation: Activation energy is the minimum energy that the reactants must have to be converted into products.
Correct answer: Activation Energy of the molecules- A. Cannot be Separated from reaction mixture
- B. Contain normal bonds
- C. Can be isolated from a reaction mixture
- D. Both B and C
Explanation: A reaction intermediate cannot be separated from the reaction mixture, as it is usually present only transiently during a…
Correct answer: Both B and C- A. Lower the activation energy
- B. Increase the activation energy
- C. Lower the pH
- D. Decrease the temp of the reaction
Explanation: A catalyst reduces the activation energy of a chemical reaction by providing an alternate route.
Correct answer: Lower the activation energy- A. Pressure
- B. Concentration of a substance
- C. Volume
- D. Temperature
Explanation: Arrhenius' equation in thermodynamics is:k = Ae-Ea/RT wherek = rate constantA = pre-exponential factorEa = activation energyR = universal…
Correct answer: Temperature- A. Highly stable
- B. Moderate stable
- C. Highly unstable
- D. In the low energy state
Explanation: The transition state (or activated complex) occurs at the maximum of the potential energy diagram along the reaction coordinate.It is a…
Correct answer: Highly unstable- A. The enthalpy
- B. The entropy
- C. The activation energy
- D. The free energy
Explanation: A catalyst provides an alternative reaction pathway with lower activation energy.This increases the reaction rate without affecting ΔH…
Correct answer: The activation energy- A. Increasing the reaction temperature.
- B. Increasing the concentration of reactants.
- C. Providing an alternative reaction pathway with a lower activation energy.
- D. Shifting the equilibrium towards the products.
Explanation: A catalyst speeds up a reaction without being consumed by providing a different mechanism or pathway for the reaction to follow.
Correct answer: Providing an alternative reaction pathway with a lower activation energy.- A. zero order reaction
- B. 1 order reaction
- C. 2 order reaction
- D. 3 order reaction
Explanation: the first order reaction does not dependent on concentration because as only one reactant is involved in rate determining step.The rate…
Correct answer: 1 order reaction