Question

Select One Option correct from the following: The half-life of $^{215} {At}$ is $100\mu s$. The time taken for the activity of a sample of $^{215} {At}$ to decay to $\frac{1}{16}$ th of its initial value is
(A) $400\mu s$
(B) $63\mu s$
(C) $40\mu s$
(D) $300\mu s$.

Answer 1

hence the answer will be option A) 400 us