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Question 19N.3.hl.TZ0.18a(ii)

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Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.3.hl.TZ0.18a(ii)
Level hl Paper 3 Time zone TZ0
Command term Explain Question number a(ii) Adapted from N/A
a(ii).
[Maximum mark: 2]
19N.3.hl.TZ0.18a(ii)

Red supergiant stars contain carbon-12 formed by the fusion of helium-4 nuclei with beryllium-8 nuclei.

Mass of a helium-4 nucleus = 4.002602 amu
Mass of a beryllium-8 nucleus = 8.005305 amu
Mass of a carbon-12 nucleus = 12.000000 amu

(a(ii))

Explain why fusion is an exothermic process.

[2]

Markscheme

ALTERNATIVE 1
binding energy per nucleon is larger in carbon-12/product «than beryllium-8 and helium-4/reactants» ✔

difference in «total» binding energy is released «during fusion» ✔

 

ALTERNATIVE 2
mass of carbon-12/product «nucleus» is less than «the sum of» the masses of helium-4 and beryllium-8 «nuclei»/reactants
OR
two smaller nuclei form a lager nucleus ✔

mass lost/difference is converted to energy «and released»
OR
E = mc2 ✔

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