Chemistry - Radioactivity Question with Solution | TestHub

The ratio of ${\mathrm{C}}^{14}$ to ${\mathrm{C}}^{12}$ in living matter is measured to be $\frac{{\mathrm{C}}^{14}}{{\mathrm{C}}^{12}}=1.3\times 10^{-12}$ at the present time. The activity of a 12.0 gm carbon sample is 180 dpm. The half-life of ${\mathrm{C}}^{14}$ is nearly

___________ $\times 10^{12}$ sec. [Given: $N_A=6\times 10^{23}$]