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Date	November 2016	Marks available	3	Reference code	16N.3.sl.TZ0.15
Level	SL	Paper	3	Time zone	TZ0
Command term	Explain and Outline	Question number	15	Adapted from	N/A

Question

Nuclear reactions transform one nuclide into another. Fission, splitting a large nucleus into two smaller nuclei, releases vast amounts of energy.

(i) Explain why fusion, combining two smaller nuclei into a larger nucleus, releases vast amounts of energy. Use section 36 of the data booklet.

(ii) Outline one advantage of fusion as a source of energy.

[3]

Radioactive phosphorus, ³³P, has a half-life of 25.3 days.

(i) Calculate ³³P decay constant λ and state its unit. Use section 1 of the data booklet.

(ii) Determine the fraction of the ³³P sample remaining after 101.2 days.

[2]

Markscheme

product has higher binding energy «per nucleon»/more stable
OR
nucleons in product more tightly bound «with one another»

lighter elements «than Fe» can fuse/combine with loss of mass/mass defect «and release vast amount of energy»

Accept “mass is converted to energy” for M2

Any one of:
deuterium/fuel is abundant/cheap
«helium» products not radioactive
fusion much less dangerous than fission
large amounts/shipments of radioactive fuel not required
far less radioactive waste «created by fast moving neutrons» has to be stored

Accept “reduces greenhouse gas emissions/global warming” OR “no radioactive waste” OR “more reliable power” OR “fewer safety issues”.
Do not accept “gives out a large amount of energy” as it is in the stem of the question.

i
« $\lambda = \frac{{\ln 2}}{{{t_{\frac{1}{2}}}}} = \frac{{0.693}}{{25.3\,{\text{days}}}} =$ » 2.74 × 10⁻² day⁻¹
Need correct unit for mark.

ii
«4 half-lives; 1 → $\frac{1}{2}$ → $\frac{1}{4}$ → $\frac{1}{8}$ → $\frac{1}{16}$ =» $\frac{1}{16}$ / 6.25 × 10⁻²
OR
« $\frac{N}{{{N_0}}} = {e^{ - {\lambda _t}}} = {e^{ - 0.0274\,\, \times \,\,101.2}} =$ » 6.25 × 10⁻²

Accept 6.25%.

Examiners report

[N/A]

Syllabus sections

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

Show 52 related questions

19N.3.hl.TZ0.18a(i):
State the nuclear equation for the fusion reaction.
17M.3.sl.TZ1.14c:
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.
18M.3.sl.TZ1.12b:
Suggest one reason why there is opposition to the increased use of nuclear fission reactors.
20N.3.sl.TZ0.10b:
The half-life of ²³⁸U is $4.46 \times 10^{9}$ years. Calculate the mass of ²³⁸U that remains after $0.639 kg$ has decayed for $2.23 \times 10^{10}$ years.
18N.3.sl.TZ0.9b.i: Outline why the term breeder is used for the reactors.
18N.3.sl.TZ0.9b.ii: Deduce the fission reaction when 239Pu is bombarded with a neutron to produce 133Xe and 103Zr.
18N.3.sl.TZ0.9a: Explain fusion reactions with reference to binding energy.
18N.3.hl.TZ0.12a: Explain fusion reactions with reference to binding energy.
18N.3.hl.TZ0.12b.ii: Deduce the fission reaction when 239Pu is bombarded with a neutron to produce 133Xe and 103Zr.
18N.3.hl.TZ0.12b.i: Outline why the term breeder is used for the reactors.
19N.3.sl.TZ0.13a(ii): Explain why fusion is an exothermic process.
17N.3.sl.TZ0.14a.i:
Compare and contrast fission and fusion in terms of binding energy and the types of nuclei involved.
17M.3.sl.TZ1.14b.i:
Deduce the identity of X.
19M.3.hl.TZ1.16a(ii):
Outline why the reaction releases energy.
19M.3.sl.TZ2.11a(i):
Determine the other product of the fission reaction of plutonium-239.
18M.3.sl.TZ2.13a:
Compare and contrast the process of nuclear fusion with nuclear fission.
19M.3.sl.TZ1.12c:
The daughter product, ⁸⁹Kr, has a half-life of 3.15 min.

Calculate the time required, in minutes, for the mass of ⁸⁹Kr to fall to 6.25 % of its initial value.
19M.3.sl.TZ1.12a(ii):
Outline why the reaction releases energy.
17M.3.sl.TZ2.12a.ii:
Explain why this fusion reaction releases energy by using section 36 of the data booklet.
19M.3.sl.TZ1.12a(i):
Write the nuclear equation for this fission reaction.
19N.3.hl.TZ0.18a(ii): Explain why fusion is an exothermic process.
17N.3.sl.TZ0.14b:
The amount of ²²⁸Ac in a sample decreases to one eighth $\left( {\frac{1}{8}} \right)$ of its original value in about 18 hours due to β-decay. Estimate the half-life of ²²⁸Ac.
19M.3.sl.TZ1.12b:
The critical mass for weapons-grade uranium can be as small as 15 kg. Outline what is meant by critical mass by referring to the equation in (a)(i).
17M.3.sl.TZ1.14b.ii:
Outline why this reaction results in a release of energy.
19N.3.hl.TZ0.18b:
Beryllium-8 is a radioactive isotope with a half-life of 6.70 × 10⁻¹⁷ s.

Calculate the mass of beryllium-8 remaining after 2.01 × 10⁻¹⁶ s from a sample initially containing 4.00 g of beryllium-8.
19M.3.sl.TZ2.11a(ii):
Outline the concept of critical mass with respect to fission reactions.
16N.3.sl.TZ0.15b:
Radioactive phosphorus, ³³P, has a half-life of 25.3 days.

(i) Calculate ³³P decay constant λ and state its unit. Use section 1 of the data booklet.

(ii) Determine the fraction of the ³³P sample remaining after 101.2 days.
19M.3.hl.TZ1.16a(i):
Write the nuclear equation for this fission reaction.
17M.3.sl.TZ1.14a:
Outline how the spectra of light from stars can be used to detect the presence of carbon.
17M.3.sl.TZ2.12a.i:
One fusion reaction occurring in the sun is the fusion of deuterium, ${}_1^2H$ , with tritium, ${}_1^3H$ , to form helium, ${}_2^4He$ . State a nuclear equation for this reaction.
19M.3.sl.TZ2.11c:
⁹⁰Sr, a common product of fission, has a half-life of 28.8 years.

Determine the number of years for the activity of a sample of ⁹⁰Sr to fall to one eighth ( $\frac{1}{8}$ ) of its initial value.
19M.3.hl.TZ2.16a(ii):
Outline the concept of critical mass with respect to fission reactions.
19M.3.sl.TZ2.11b:
State one advantage of using fusion reactions rather than fission to generate electrical power.
18N.3.hl.TZ0.12c:
Nuclear disasters release radioactive caesium into the atmosphere, which presents serious health risks.

Cs-137 has a half-life of 30 years.

Calculate the percentage of Cs-137 remaining in the atmosphere after 240 years.
17N.3.sl.TZ0.14a.ii:
Suggest two advantages that fusion has over fission.
19M.3.hl.TZ1.16b:
The critical mass for weapons-grade uranium can be as small as 15 kg. Outline what is meant by critical mass by referring to the equation in (a)(i).
19M.3.hl.TZ2.16a(i):
Determine the other product of the fission reaction of plutonium-239.

${}_{94}^{239}{\text{Pu + }}{}_0^1{\text{n}} \to {}_{54}^{134}{\text{Xe + }}.................{\text{ + 3}}_0^1{\text{n}}$
19M.3.hl.TZ2.16a(iii):
Outline one advantage of allowing all countries access to the technology to generate electricity by nuclear fission.
19N.3.sl.TZ0.13a(i):
State the nuclear equation for the fusion reaction.
20N.3.hl.TZ0.12d:
Deduce the nuclear equation for the decay of uranium-238 to thorium-234.
18M.3.sl.TZ2.13b:
Dubnium-261 has a half-life of 27 seconds and rutherfordium-261 has a half-life of 81 seconds.

Estimate what fraction of the dubnium-261 isotope remains in the same amount of time that $\frac{3}{4}$ of rutherfordium-261 decays.
19M.3.sl.TZ2.11a(iii):
Outline one advantage of allowing all countries access to the technology to generate electricity by nuclear fission.
19M.3.hl.TZ2.16b:
State one advantage of using fusion reactions rather than fission to generate electrical power.
19N.3.sl.TZ0.13b:
Beryllium-8 is a radioactive isotope with a half-life of 6.70 × 10⁻¹⁷ s.

Calculate the mass of beryllium-8 remaining after 2.01 × 10⁻¹⁶ s from a sample initially containing 4.00 g of beryllium-8.
20N.3.hl.TZ0.12e: Thorium-234 has a higher binding energy per nucleon than uranium-238. Outline what is meant...
20N.3.sl.TZ0.10e: Thorium-234 has a higher binding energy per nucleon than uranium-238. Outline what is meant...
20N.3.sl.TZ0.10c: Outline a health risk produced by exposure to radioactive decay.
20N.3.sl.TZ0.10d:
Deduce the nuclear equation for the decay of uranium-238 to thorium-234.
18M.3.sl.TZ1.12a.ii:
Explain how ²³⁵U fission results in a chain reaction, including the concept of critical mass.
20N.3.hl.TZ0.12c: Outline a health risk produced by exposure to radioactive decay.
18N.3.sl.TZ0.9c:
Nuclear disasters release radioactive caesium into the atmosphere, which presents serious health risks.

Cs-137 has a half-life of 30 years.

Calculate the percentage of Cs-137 remaining in the atmosphere after 240 years.
20N.3.hl.TZ0.12b:
The half-life of ²³⁸U is $4.46 \times 10^{9}$ years. Calculate the mass of ²³⁸U that remains after $0.639 kg$ has decayed for $2.23 \times 10^{10}$ years.

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