2016 · M/J · 5054/22 | Q11

75-mark sittingChoose two Section B questions; practice marks across routes are not combined.

Question 1115 marks · Practise this topic →

Options

Available practice: 71 of 75 marks. Parts 5(a)(ii), 5(b)(i), 11(a) await marking support. Scores cover available parts only. Theory Paper 2: Section A is compulsory and Section B offers a choice of two questions. Four published mark-scheme discrepancies across the two variants are held from automatic marking.

(a)Fig. 11.1 represents a nuclear fusion reaction. At very high temperatures, nuclei of the two isotopes 12H and 13H fuse together. Energy is produced and two new particles are formed, particle A and particle B. Explain what is meant by isotopes of hydrogen.

Fig. 11.1 — see the question text for what it shows

Answer guidance

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

[2 marks]

This part is shown as printed, but its marks conflict with the published mark scheme. It is not scored.

(b)(i)Using the hydrogen-fusion reaction in Fig. 11.1, state the number of neutrons in a nucleus of hydrogen-3.

Answer guidance

Using You must use the thing it names. An answer that reaches the right value another way may not score.

[1 mark]

(b)(ii)Using the hydrogen-fusion reaction in Fig. 11.1, name particle A.

Answer guidance

Using You must use the thing it names. An answer that reaches the right value another way may not score.

[1 mark]

(b)(iii)Using the hydrogen-fusion reaction in Fig. 11.1, state the proton number of particle B.

Answer guidance

Using You must use the thing it names. An answer that reaches the right value another way may not score.

[1 mark]

(b)(iv)Using the hydrogen-fusion reaction in Fig. 11.1, state the nucleon number of particle B.

Answer guidance

Using You must use the thing it names. An answer that reaches the right value another way may not score.

[1 mark]

(c)Fig. 11.1 represents a nuclear fusion reaction. At very high temperatures, nuclei of the two isotopes 12H and 13H fuse together. Energy is produced and two new particles are formed, particle A and particle B. A very high temperature is needed to force nuclei together. Explain why.

Answer guidance

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

[2 marks]

(d)Fig. 11.1 represents a nuclear fusion reaction. At very high temperatures, nuclei of the two isotopes 12H and 13H fuse together. Energy is produced and two new particles are formed, particle A and particle B. A star forms from a large cloud of gas and dust in space. Describe what happens as the star forms.

Answer guidance

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

[3 marks]

(e)(i)Fig. 11.1 represents a nuclear fusion reaction. At very high temperatures, nuclei of the two isotopes 12H and 13H fuse together. Energy is produced and two new particles are formed, particle A and particle B. The isotope of hydrogen 13H has a half-life of 12 years. State what is meant by half-life.

Answer guidance

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

[2 marks]

(e)(ii)A sample initially contains 16 000 atoms of hydrogen-3, whose half-life is 12 years. Calculate how many hydrogen-3 atoms remain after 48 years.

Answer guidance

Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.

[2 marks]

5054/22/M/J/16Cambridge O Level Physics 5054 · May/June 2016 · Paper 2 variant 2 · Question 11