CAIE A Level Chemistry 9701 · States of matter
Ice is a crystalline solid. Unlike most substances, its solid form is less dense than its liquid form, so ice floats on water.
Describe the lattice structure of ice and use your description to explain why ice is less dense than liquid water.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.