CAIE A Level Chemistry 9701 · States of matter
Two crystalline solids are described below.
Solid A melts at 801 °C. It does not conduct electricity when solid, but it conducts when molten.
Solid B sublimes at 113 °C. It is an insulator both when solid and when molten.
Explain, in terms of structure and bonding, the differences between A and B in melting point and electrical conductivity.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.