Question

The half life of a certain radioactive element is 1 year. The percentage of the radioactive element decayed in 6 months will be–

• A. 29.3 %
• B. 39.5 %
• C. 70.5 %
• D. 14.5%

Answer 1

Answer: (A)

29.3 %

Answer 2

N = N₀ e^–lt

= N₀

= N₀

N =

Decayed = N₀ – N = N₀ (1 – $\frac { 1 } { \sqrt { 2 } }$)= N₀ (1 – 0.707) = 0.293 N₀ ̃ 29.3%