If the radioactive decay constant of a radioactive substance is 0.00693 per year, what is the half-life of the substance?

(ln2 = 0.693)

Correct option is C

​$$\begin{aligned}&\textbf{ Given Data:} \\&\text{Decay constant, } \lambda = 0.00693 \, \text{year}^{-1} \\&\text{Natural logarithm of 2, } \ln 2 = 0.693 \\&\text{The half-life } (t_{1/2}) \text{ of a radioactive substance is related to the decay constant by:} \\&t_{1/2} = \frac{\ln 2}{\lambda} \\\\&t_{1/2} = \frac{0.693}{0.00693} \\\\&t_{1/2} = \frac{0.693}{0.00693} = 100 \, \text{years}\end{aligned}$$​​