Question

The mean life time of a radionuclide, if its activity decreases by $4$% for every $1h$, would be (product is non-radioactive, i.e., stable)

• A. $25h$
• B. $1.042h$
• C. $2h$
• D. $30h$

Answer 1

The correct option is A $25h$

Product is stable and non radioactive, hence decay is linear and not exponential.
$4$% decay in one hour.
For $100$% decay we would need $\frac{100}{4}\times 1=25$ hours