Question

A sample of radioactive element containing 4×1016 active nuclei. Half-life of the element is 10 days, then the number of decayed nuclei after 30 days

• A. 0.5 × 1016
• B. 2 × 1016
• C. 3.5 × 1016
• D. 1 × 1016

Answer 1

Answer: (C)

3.5 × 1016

Answer 2

The correct option is (C) : 3.5 × 1016

t = nT, X = $\frac{X_0}{2^m}n$ =$\frac{t}{T}$=$\frac{30}{10}$=3 , Active nuclei X = $\frac{4\times10^{16}}{(2)^3}$ and decayed nuclie X = (X0 – X) = 3.5 × 1016