2023 · O/N · 5054/22 | Q9

0/40parts marked · 0 of 80 marks

Question (9 of 10)10 marks · Practise this topic →

Options

Theory: answer each printed part. For drawings, upload a clear photo of your sketch on the supplied figure; show working and units for calculations.

(a)

An interstellar dust-and-gas cloud containing hydrogen collapses to form a protostar.

Describe the energy transfers as the cloud collapses to form a protostar.

Answer guidance

Describe Say what happens, in order. Reasons are not required unless the question also asks why.

[2 marks]

(b)(i)

The protostar contains radioactive hydrogen-3. State how nuclei of isotopes of the same element differ.

Answer guidance

State A short answer. No explanation is needed, and adding one cannot earn extra marks.

[1 mark]

(b)(ii)

Explain why hydrogen-3 cannot decay by alpha emission.

Answer guidance

Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.

[1 mark]

(b)(iii)

Complete the missing nuclide numbers in the beta-decay equation for hydrogen-3 to helium: ³₁H → ___β + ___He.

Answer guidance

Complete Fill in every gap. A partly completed answer usually scores partly.

[2 marks]

(b)(iv)

Explain how the nuclear reaction stops further collapse as the protostar becomes a stable star.

Answer guidance

Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.

[3 marks]

(c)

State which part of a star’s life cycle produces the heaviest elements.

Answer guidance

State A short answer. No explanation is needed, and adding one cannot earn extra marks.

[1 mark]

5054/22/O/N/23Cambridge O Level Physics 5054 · Oct/Nov 2023 · Paper 2 variant 2 · Question 9