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GCSE Questions: Radioactivity

Q16. Polonium-210 ( ) is a radioactive isotope that decays by emitting alpha radiation.

(a) Which is the correct decay equation for polonium-210? (Tick one box).

[1 mark]

(b) Why is alpha radiation dangerous inside the human body?

Alpha radiation is highly ionising.

It therefore can damage DNA strands and cause cancer. But the examiner asked why it is dangerous, now how that danger manifests itself. The mark went for it being 'highly ionising'.

[1 mark]

(c) The graph below shows how the mass of a sample of polonium-210 changes with time.

(i) Determine the change in mass of the sample of polonium-210 between 50 and 150 days.

460 - 280 = 180 mg

[2 marks]

(ii) Estimate the mass of polonium-210 remaining after 300 days.

The examiners allowed any answer between 126 and 150 (mg) inclusive.

See the graph - you needed to extend the line smoothly.

130 mg

[1 mark]

(d) Nuclear radiation can cause ionisation.

(i) How does the charge of an ion differ from the charge of an atom?

An atom has a net zero charge, whereas an ion has either negative (anion) or positive (cation) net charge.

(ii) How does an atom becomes an ion?

To become a cation it loses an electron. To become an anion it gains an electron.

The key idea is that it is electron gain or loss that creates an ion from an atom.

[3 marks]

(Total 8 marks)