A radioactive source registers counts per minute at

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

Problem

A radioactive source registers

800

counts per minute at

t=0

. Nine minutes later the count rate is

200

counts per minute. Assuming exponential decay, which of the following is closest to the sample’s half-life? (a)

6.5\,\text{min}

(b)

2.3\,\text{min}

(c)

4.5\,\text{min}

(d)

9\,\text{min}