Two pure radioactive isotopes A and B each contain the same number of nuclei at

PHYSICS · Single correct · A Level · Physics · Nuclear physics · Nuclear physics

Problem

t=0

. The half-life of A is

2\,\text{days}

, while that of B is

5\,\text{days}

. Calculate, to two significant figures, the ratio of their activities

\dfrac{A_A}{A_B}

after

4\,\text{days}

. (a) 5.7 (b) 0.44 (c) 1.1 (d) 2.5