Compare and contrast the process of nuclear fusion with nuclear fission.

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.

Award [1] for one similarity:

both increase binding energy/energy yield «per nucleon»

OR

mass loss/defect in both «nuclear» reactions/mass converted to energy «from E = mc²»

OR

both produce ionizing radiation

Award [2 max] for any two differences:

in fusion, light nuclei combine to form heavier ones AND in fission, heavier nuclei split into lighter ones

fission produces radioactive/nuclear waste AND fusion does not

fission is caused by bombarding with a neutron «or by spontaneous fission» AND fusion does not

OR

fission can initiate a chain reaction AND fusion does not

fusion releases more energy per unit mass of fuel than fission

fuel is easier to obtain/cheaper for fusion reactions

fission reactions can be controlled in a power plant AND fusion cannot «yet»

fusion reactor less likely to cause a large-scale technological disaster compared to fission

fusion less dangerous than fission as radioactive isotopes produced have short half-lives so only cause a threat for a relatively short period of time

fusion is in experimental development AND fission used commercially

Accept “small nuclei” OR “smaller atomic masses of nuclei” for “light nuclei” AND “large nuclei” OR “greater atomic masses of nuclei” for “heavier nuclei”.

Do not accept “no/less waste produced for fusion”.

Accept “higher specific energy for fusion”.

[3 marks]

\(\frac{1}{{64}}\)/\(\frac{1}{{{2^6}}}\)/0.016

Accept “1.6%”.

[1 mark]