Question

Plutonium decays with half life of 2400 years if plutonium is stored for 72000 years, the fraction of it that remains is.

• A. 1/8
• B. 1/3
• C. 1/4
• D. 1/2

Answer 1

Answer: (A)

1/8

Answer 2

: here, $n = \frac{72000}{24000} = 3,\frac{N}{N_{0}} = \left( \frac{1}{2} \right)^{n} = \left( \frac{1}{2} \right)^{3} = \frac{1}{8}$