Nuclide decays to nuclide with decay constant

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

Problem

Nuclide

A

decays to nuclide

B

with decay constant

\lambda_A=0.040\,\text{s}^{-1}

. Nuclide

B

decays to a stable product with decay constant

\lambda_B=0.10\,\text{s}^{-1}

. Assuming the sample is initially pure

A

, at what time after the start of the decay chain is the activity of

B

greatest? (a)

6.9\,\text{s}

(b)

25\,\text{s}

(c)

15\,\text{s}

(d)

11.6\,\text{s}