Physics 0625 · IGCSE · Radioactivity

Radioactivity — practice question

A number of domestic smoke alarms include a sample of the radioactive isotope americium-241 (Am).
(a(i))[1]

State in what way the composition of the nucleus of americium-241 is different from that of the nucleus of americium-242.

(a(ii))[2]

State two ways in which the nucleus of this atom differs in composition from a nucleus of americium-241.

(b(i))[3]

Complete this decay equation: $^{241}_{95}\text{Am} \rightarrow {}^{?}_{93}\text{Np} + {}^{?}_{2}\alpha$.

(b(ii))[2]

Explain why $\alpha$-particles ionise more strongly than $\beta$-particles.

(b(iii))[2]

Using this information, explain the benefit of this long half-life for the operation and safe disposal of a household smoke alarm.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Americium-241 contains one fewer neutron

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