Question

The half-life for a reaction is 50 minutes. If the initial concentration is halved, the half-life becomes 25 minutes. Then it is a order reaction.

• A. zero
• B. first
• C. second

Answer 1

The correct option is A zero

Half-life, i.e, $t_{\frac{1}{2}}$ is proportional to the initial concentration only for a zero order reaction.
For a zero order reaction,
$t_{\frac{1}{2}}$ $\propto$ $\left[A_0\right]$
where, $\left[A_0\right]$ is the initial concentration