Question

The activity of a radioactive sample decreases to 25% of its initial value in 60 days. The half-life is:

• A. 30 days
• B. 60 days
• C. 20 days
• D. 40 days

Hint:

25% remaining means two half-lives have passed.

Answer 1

The Correct Option is A

25% = \((1/2)^2\), so 2 half-lives = 60 days. \[ T_{1/2} = 30\ \text{days} \]