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Date May 2017 Marks available 1 Reference code 17M.3.sl.TZ1.14
Level SL Paper 3 Time zone TZ1
Command term Deduce Question number 14 Adapted from N/A

Question

Carbon is produced by fusion reactions in stars.

The main fusion reaction responsible for the production of carbon is:

X + 2 4 He 6 12 C

Outline how the spectra of light from stars can be used to detect the presence of carbon.

[1]
a.

Deduce the identity of X.

[1]
b.i.

Outline why this reaction results in a release of energy.

[1]
b.ii.

Nuclear fusion reactors are predicted to become an important source of electrical energy in the future. State two advantages of nuclear fusion over nuclear fission.

[2]
c.

Markscheme

presence of dark/absorption lines corresponding to those found for carbon
OR
missing wavelengths/frequencies correspond to carbon’s spectrum

 

Accept “presence of characteristic dark lines”.

Do not accept answer in terms of emission spectra.

[1 mark]

a.

4 8 B e

[1 mark]

b.i.

product «nucleus» has a greater binding energy «per nucleon than reacting nuclei»

 

Accept “mass of the products is less than mass of the reactants”.

Accept converse arguments.

[1 mark]

b.ii.

fuel more abundant/cheaper

no «long half-life» radioisotopes/radioactive waste

shipment of radioactive fuels not required

plutonium/nuclear weapons cannot be produced from products

nuclear disasters less likely «as no critical mass of fuel required»

higher specific energy/energy per g/kg/unit mass than fission

 

Do not accept simply “fusion produces more energy than fission”.

[2 marks]

c.

Examiners report

[N/A]
a.
[N/A]
b.i.
[N/A]
b.ii.
[N/A]
c.

Syllabus sections

Options » C: Energy » C.3 Nuclear fusion and fission
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