Two radioisotopes P and Q have decay constants and respectively

PHYSICS · Subjective · A Level · Physics · Nuclear physics · Nuclear physics

Problem

Two radioisotopes P and Q have decay constants

4.0\times10^{-3}\,\text{s}^{-1}

and

2.0\times10^{-3}\,\text{s}^{-1}

respectively. Which isotope has the longer half-life? Give a brief reason for your answer.