Question

What is order of radioactive decay of a substance ?

• A. \(0\)
• B. \(1\)
• C. \(1.5\)
• D. \(2\)

Hint:

Radioactive decay rate is proportional to the number of nuclei present.

Answer 1

The Correct Option is B

Step 1: Rate law:
$\text{rate} = \lambda N^1$.

Step 2: Half life test:
$t_{1/2} = 0.693/\lambda$ is constant for any amount of sample, which only happens for first order processes.

Step 3: Result:
Order is 1, option (B).

Final Answer:
Radioactive decay is first order. \[ \boxed{\text{(B) }1} \]