Physics 9702 · AS & A Level · Radioactive decay

Radioactive decay — practice question

(a)[3]

Distinguish, for an atom, the nucleus from a nucleon.

(b)

Radon gas is a naturally occurring radioactive gas whose half-life is $3.8$ days. The measured activity of radon gas in a room is $97\,\text{Bq}$ in each $1.0\,\text{m}^3$ of air.

(b(i).1)[2]

Calculate the decay constant of radon, in $\text{s}^{-1}$.

(b(i).2)[2]

Calculate the number of radon atoms that produce an activity of $97\,\text{Bq}$.

(b(i)(1))[2]

Radon gas is a naturally occurring radioactive gas whose half-life is $3.8\ \text{days}$. The activity of radon gas in a room is measured to be $97\ \text{Bq}$ in each $1.0\ \text{m}^3$ of air. Calculate the decay constant, in $\text{s}^{-1}$, of radon.

(b(i)(2))[2]

Calculate the number of radon atoms that produce an activity of $97\ \text{Bq}$.

(b(ii))[2]

Using a volume of $1.0\ \text{m}^3$ of air, determine the ratio $$\frac{\text{number of radon atoms}}{\text{number of air molecules}}.$

Worked solution & mark scheme

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