Question

Radium has a half-life of $5years$ . The probability of decay of a radium nucleus in $10years$ is

• A. $50\%$
• B. $75\%$
• C. $100\%$
• D. $60\%$
• E. $25\%$

Answer 1

Answer: (B)

$\frac{N}{N_0}={\left(\frac{1}{2}\right)}^{t/T}={\left(\frac{1}{2}\right)}^{\frac{10}{5}}={\left(\frac{1}{2}\right)}^2=\frac{1}{4}=25$
This is probability of remaining portion of radium. So, probability of decay
$=(100-25)$