Physics - Modern Physics Question with Solution | TestHub

Half life, $\mathrm{T}=15$ days, time $\mathrm{t}=60$ days $=4\mathrm{T}$ The number of nuclei remaining is given by $$\begin{array}{rl}& \mathrm{N}={\mathrm{N}}_0{\left(\frac{1}{2}\right)}^{\mathrm{n}}={\mathrm{N}}_0{\left(\frac{1}{2}\right)}^4=\frac{1}{16}\times 8\times 10^{16}\\ & =0.5\times 10^{16}\\ & \therefore \text{ No. of nuclei decayed }={\mathrm{N}}_0-\mathrm{N}\\ & =8\times 10^{16}-0.5\times 10^{16}=7.5\times 10^{16}\end{array}$$