Physics

Problem

In a semi-log plot (natural logarithm) of activity

A

versus time

t

for a radioactive isotope, the straight line has a slope of

-0.045\,\text{min}^{-1}

. The half-life

t_{1/2}

of the isotope is closest to a)

7.0\,\text{min}

15\,\text{min}

22\,\text{min}

31\,\text{min}