Question

The decay constant of a radioactive sample is $\lambda$. The half-life and average-life of the sample are respectively

• A. $1/\lambda$ and (In 2$\lambda$)
• B. (In 2/$\lambda$ ) and 1 /$\lambda$
• C. 1 (In 2) and 1 / $\lambda$
• D. $\lambda$/ (In 2) and 1 / $\lambda$

Answer 1

The correct option is B (In 2/$\lambda$ ) and 1 /$\lambda$

Half life will be $\frac{0.693}{\lambda }=ln2/\lambda$

Average life is reciprocal of $\lambda$ i.e. $1/\lambda$

Option B is correct.