Question

A certain radioactive substance has a half-life of 5 years. Thus for a nucleus in a sample of the element, the probability of decay in ten years is

• A. 0.5
• B. 0.75
• C. 1
• D. 0.6

Answer 1

Answer: (B)

0.75

Answer 2

In 10 years the number of undecayed particles will be $N_0 /4$. That is number of decayed particles will be 3$N_0 /4$ . Hence probability of decay will be 75%.