| Date | November 2017 | Marks available | 2 | Reference code | 17N.3.sl.TZ0.14 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Compare and contrast | Question number | 14 | Adapted from | N/A |
Question
In the 20th Century, both fission and fusion were considered as sources of energy but fusion was economically and technically unattainable.
Compare and contrast fission and fusion in terms of binding energy and the types of nuclei involved.
Suggest two advantages that fusion has over fission.
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.
Markscheme
Fission: heavy nuclei AND Fusion: light nuclei
both increase in binding energy/energy yield «per nucleon»
Accept “large nuclei” OR “greater atomic masses of nuclei” for fission AND “small nuclei” OR “smaller atomic masses of nuclei” for fusion.
Award [1 max] for “Fission: heavy nuclei AND increase in binding energy «per nucleon»” OR “Fusion: light nuclei AND increase in binding energy” «per nucleon»”.
Any two of:
no/less radioactive waste produced
abundance/low cost of fuel
larger amounts of energy released per unit mass
does not require a critical mass
can be used continuously
fusion reactor less likely to cause large-scale technological disaster
Do not accept "no/less waste produced".
Accept “higher specific energy”.
[Max 2 Marks]
6 «hours»
