Question

half life of a radioactive substance A is 4 days. the probability that a nucleus will decay in two half lives is:

• A. 1/4
• B. $\frac{e^2-1}{e^2}$
• C. 3/4
• D. 2/5

Answer 1

Answer: (C)

The correct option is C 3/4
$\begin{array}{c}Aftertwohalflives\frac{1^{th}}{4}fractionofnucleiwillremainundecayed\\ or,\frac{3^{th}}{4}fractionwilldecay\\ hencetheprobabilitythatanucleusdecaysintwohalflivesis\frac{3}{4}\end{array}$

Hence,

option $\left(C\right)$ is correct answer.