Q. Half life of $Bi^{210}$ is $5\ days$. If we start with 50,000 atoms of this isotope, the number of atoms left over after $10\ days$ is
A) 5,000
B) 25,000
C) 12,500
D) 20,000
Explanation
(c) $N_{t} = N_{0}\left( \frac{1}{2} \right)^{t/T} = 50000\left( \frac{1}{2} \right)^{10/5} = 12500$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.