Question

The percentage of radioactive substance left after 5 half lives is

• A. 0.31
• B. 0.03125
• C. 0.003
• D. 0.01

Answer 1

Answer: (B)

0.03125

Answer 2

$\frac{N}{N_0} = \left( \frac{1}{2} \right)^5 = \frac{1}{32} = \frac{1}{3^2} = M \frac{100}{32}$