Physics - Modern Physics Question with Solution | TestHub

Half life number is given by $n=\frac{1}{T}$ $=\frac{30}{10}=3$ Nuclear of active nuclei left after $\mathrm{n}$ half-life is $$\begin{array}{rl}& N=N_0{\left(\frac{1}{2}\right)}^n\\ =& \frac{4\times 10^{16}}{(2{)}^3}=0.5\times 10^{16}\\ \therefore & \text{ Decay nuclei }=N_0-N\\ =& 4\times 10^{16}-0.5\times 10^{16}\\ =& 3.5\times 10^{16}\end{array}$$