Question

Which among the following is a false statement ?

• A. Rate of zero order reaction is independent of initial concentration of reactant.
• B. Half-life of a zero order reaction is inversely proportional to the rate constant.
• C. Molecularity of a reaction may be zero.
• D. For a first order reaction, $t_{1/2} = 0.693/k$.

Hint:

For reaction orders, remember that molecularity and order are often confused. Molecularity refers to the number of molecules involved in the reaction, while order refers to the powers of concentrations in the rate law.

Answer 1

The Correct Option is C

Statement (1) is accurate; for zero-order reactions, the rate is unaffected by reactant concentration.
Statement (2) is also correct; the half-life of a zero-order reaction, $t_{1/2} = [A]_0 / 2k$, demonstrates an inverse relationship with the rate constant.
Statement (3) is incorrect because molecularity, defined as the count of reacting molecules, cannot be zero in a valid reaction.
Statement (4) is true; for a first-order reaction, the half-life is $t_{1/2} = 0.693/k$.
Therefore, statement (3) is false.