CAIE A Level Chemistry 9701 · States of matter
A white crystalline solid X melts at 801 °C. Solid X does not conduct electricity, but molten X is a good conductor. X dissolves in water, and the aqueous solution also conducts electricity.
Explain these observations in terms of the structure and bonding of X, and deduce the type of structure present in X.
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.