22 practice MCQs on rate of reaction, rate law and order, activation energy, catalysts and collision theory. Every question has the correct answer and an explanation.
Start free — 20 questionsReaction Kinetics is part of the MDCAT Chemistry syllabus. This page collects Reaction Kinetics MCQs in the style of past MDCAT papers — below are 12 of them with answers and explanations, and the full set of 22 questions is in the HighYield MDCAT QBank.
This chapter covers: rate of reaction, rate law and order, activation energy, catalysts and collision theory.
Correct answer: A. Lower the activation energy
A catalyst functions by lowering the activation energy of a reaction, providing an alternative pathway that speeds up the rate without being consumed.
Correct answer: D. Autocatalysis
Autocatalysis occurs when a product formed during a reaction itself acts as a catalyst, accelerating the reaction as it proceeds.
Correct answer: D. 48 minutes
With a half-life of 24 minutes, decay to 25% (two half-lives, since 100% to 50% to 25%) takes 2 × 24 = 48 minutes.
Correct answer: A. 2nd order reaction
Since Rate = k[A]²[B], the reaction is second order with respect to A, based on the exponent of [A] in the rate law.
Correct answer: D. Vanadium pentoxide
Vanadium pentoxide (V2O5) is the catalyst used in the Contact Process to convert sulphur dioxide to sulphur trioxide.
Correct answer: D. Iron crystals with metal oxide promoters
The Haber process uses finely divided iron, with metal oxide promoters (such as K2O and Al2O3), as the catalyst for ammonia synthesis.
Correct answer: B. H₂SO₄
Concentrated sulphuric acid (H2SO4) acts as the acid catalyst in the Fischer esterification of acetic acid with ethanol.
Correct answer: C. V2O5
The Contact Process involves the oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3), which is then used to produce sulfuric acid.SO2 obtained by burning sulphur or iron pyrites is oxidized to SO3 in the presence of V2O5 which acts as a catalyst.
Correct answer: B. Average rate of reaction
The average rate of reaction is calculated by taking the ratio of the change in concentration of reactants or products over a specific time interval. It represents the overall rate of reaction during that time interval. The average rate of reaction is often calculated using the initial and final concentrations of reactants or products.
Correct answer: C. Greater
The correct option is C, greater. If the slope of the curve is greater near the start of the reaction, it indicates a rapid initial reaction rate.
Correct answer: A. Change in concentration of substance/Time taken for the change
The rate measures how fast a reaction occurs, which means we need to determine how much the concentration of a reactant or product changes per unit of time.Dividing the change in concentration by time gives the rate in correct units (e.g., mol/L·s), showing how quickly reactants are consumed or products are formed.
Correct answer: C. To produce cis alkene
Lindlar's catalyst is specifically designed for the partial hydrogenation of alkynes to form cis-alkenes. It does this by providing a controlled environment where hydrogenation occurs without over-reduction to alkanes, ensuring the formation of the cis configuration.
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