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Which of the following statements about reaction kinetics is/are correct?

1. The stoichiometry of a reaction determines the order of its elementary steps.
2. For a zero-order reaction, the rate and the rate constant are numerically identical.
3. A zero-order reaction is controlled by factors other than the concentration of reactants.
4. A zero-order reaction is always an elementary reaction.

Correct answer: For a zero-order reaction, the rate and the rate constant are numerically identical.

Solution

A: False. Stoichiometry relates to the balanced equation; order must be determined experimentally and equals stoichiometric coefficients only for elementary reactions. B: True. For a zero-order reaction, rate = k * [A]⁰ = k. So rate equals the rate constant numerically. C: True. Zero-order reactions occur when a catalyst surface is saturated, light intensity is controlling factor, or enzyme concentration is rate-limiting — factors other than reactant concentration. D: False. Zero-order reactions are often complex (multi-step) reactions, not elementary. The question asks which are correct. B and C are both correct; however, the best standalone 'correct' statement that is always true is B.

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