Q. Radium has a half-life of 5 yr. The probability of decay of a radium nucleus in 10 yr is
A) 50 %
B) 75%
C) 100%
D) 60%
Explanation
(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
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = (10$0-25)%= 75%
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.