Chemistry - Chemical Kinetics Question with Solution | TestHub

The half-life ($t_{1/2}$) for a first-order reaction, like radioactive decay, is constant.

From the assertion, 500 mg to 250 mg is one half-life, so $t_{1/2}=120$ minutes.

For 100 mg to become 50 mg, it also takes one half-life, which is 120 minutes, not 24 minutes.

Thus, the Assertion is false. The Reason is true because radioactive decay follows first-order kinetics.