Question

In a sample of radioactive material what fraction of the initial number of active nuclei will remain undisintegrated after half of a half- life of sample?

• A. $1/4$
• B. $1/\sqrt{2}$
• C. $1/2$
• D. $\sqrt{2}-1$

Answer 1

The correct option is B $1/\sqrt{2}$

Fraction undecayed is $\frac{1}{2^{0.5t_{1/2}/t_{1/2}}}=1/2^{0.5}=1/\sqrt{2}$