Q. The decay constant of radium is $4.28 \times 10^{- 4}per\ year$. Its half life will be
A) $2000\ years$
B) $1240\ years$
C) $63\ years$
D) $1620\ years$
Explanation
(d) $T = \frac{0.6931 \times 1}{\lambda} = \frac{0.6931}{4.28 \times 10^{- 4}}year = 1620\ years$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.