Question 22M.2.sl.TZ2.4a(ii)
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.sl.TZ2.4a(ii) |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | a(ii) | Adapted from | N/A |
Carbon forms many compounds.
C60 and diamond are allotropes of carbon.
Explain why C60 and diamond sublime at different temperatures and pressures.
[2]
diamond giant/network covalent AND sublimes at higher temperature ✔
C60 molecular/London/dispersion/intermolecular «forces» ✔
Accept “diamond has strong covalent bonds AND require more energy to break «than intermolecular forces»” for M1.
This was the most challenging question on the paper. A teacher commented that the wording of the question could be clearer. The markscheme was simplified to give candidates the best opportunity to score at least one out of the two marks. The average mark for this question was 0.3 out of 2 marks. The answers were rather general and contained many errors. Many candidates stated that both C60 and diamond were giant covalent or both had intermolecular forces. There was also mention of ionic bonds. Some candidates were clear about the bonding but discussed melting point instead of sublimation as directed by the question losing one of the 2 marks.
