Question

Radioactive decay is a
(a) first order reaction
(b) zero order reaction
(c) second order reaction
(d) third order reaction

Answer 1

Answer : (a) first order reaction

explanation : rate of radioactive decay is directly proportional to number of nuclei present in the sample.

e.g., $\frac{dN}{dt}\propto-N$ where negative sign indicates that rate of decay of nuclei , N is the number of nuclei present in the sample.

so, $\frac{dN}{dt}=-\lambda N$
here $\lmbda$ indicates that radioactive decay constant.

here from rate equation, it is clear that, radioactive decay is a first order reaction.