Question

Three fourth of the active decays in a radioactive sample in 3/4 sec. The half life of the sample is.

• A. $\frac{1}{2}$ sec
• B. 1 sec
• C. $\frac{3}{8}$ sec
• D. $\frac{3}{4}$ sec

Answer 1

Answer: (C)

$\frac{3}{8}$ sec

Answer 2

$\frac{3}{4}th$ active decay takes place in time

$t = 2(T_{1/2})$ ⇒ $\frac{3}{4} = 2(T_{1/2})$ ⇒ $T_{1/2} = \frac{3}{8}\sec$.