Physics 9702 · AS & A Level · Radioactive decay

Radioactive decay — practice question

(a)[3]

Distinguish, for an atom, between a nucleus and a nucleon.

(b)

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

(b(i).1)[2]

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(i)1)[2]

Radon gas is a naturally occurring radioactive gas with a half-life of $3.8\ \text{days}$. In a room, the activity of radon gas is measured as $97\ \text{Bq}$ 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]

A volume of $2.5 \times 10^{-2}\ \text{m}^3$ of air in the room contains $1.0\ \text{mol}$ of molecules. Determine the ratio, for $1.0\ \text{m}^3$ of air, $\dfrac{\text{number of radon atoms}}{\text{number of air molecules}}$.

Worked solution & mark scheme

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