A-LevelPhysicsNuclear physics9702/42 · Oct/Nov 2018 · Q128 Marks

State what is meant by nuclear fusion and nuclear fission.

(a)State what is meant by nuclear fusion and nuclear fission.[3]
(b)(i)A nuclear reaction which may, in the future, be used for the generation of electrical energy is ²₁H+³₁H → ⁴₂He+x. Name the particle x.[1]
(b)(ii) 1.Data for the binding energy per nucleon Eᴮ of some nuclei are given in Fig. 12.1. [Figure 12.1] State the binding energy per nucleon of x.[1]
(b)(ii) 2.Data for the binding energy per nucleon Eᴮ of some nuclei are given in Fig. 12.1. [Figure 12.1] Calculate the energy change that takes place in this reaction.[3]
(b)(iii)Use your answer in (ii) part 2 to determine the energy release when 2.0 g of deuterium (²₁H) reacts with 3.0 g of tritium (³₁H).[1]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.

[B1] fusion: two nuclei combine to form a (single) nucleus
[B1] fission: a (single) large nucleus divides to form (smaller) nuclei
[B1] Any one from: • fusion is initiated by (very) high temperatures • fission is initiated by neutron bombardment • resulting nuclei in fission are of similar size • (both processes) release energy • binding energy per nucleon increases • total binding energy increases • fission involves release of neutrons
[B1] neutron
[A1] zero
[C1] (4 × 11.3290 × 10⁻¹³) – (2 × 1.7813 × 10⁻¹³) – (3 × 4.5285 × 10⁻¹³)
[A1] energy change = 45.316 × 10⁻¹³ – 17.148 × 10⁻¹³ = 2.82 × 10⁻¹² J
[A1] 1.0 mol or N_A nuclei of each energy = 2.817 × 10⁻¹² × 6.02 × 10²³ = 1.7 x 10¹² J

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