Physics - Modern Physics Question with Solution | TestHub

When $40\%$ nuclei decay, $60\%$ nuclei remain undecayed Let this number be ${\mathrm{N}}_0$ When $85\%$ nuclei decay, $15\%$ nuclei remain undecayed This number will be $\mathrm{N}=\frac{{\mathrm{N}}_0}{4}$ The number of nuclei will become one-fourth in two half-lives i.e., 60 minutes.