JAMB - Chemistry (2004 - No. 1)
When a solid substance disappears completely as a gas on heating, the substance is said to have undergone
evaporation
distillation
crystallization
sublimation
Paliwanag
Evaporation is a change of state from a liquid to a gas.
Distillation is a physical process that involves a phase change from liquid to gas (vapour) and then back to liquid.
Crystallization is a physical change that occurs when a substance turns from a liquid to a solid crystal.
Sublimation is a change of state from a solid to a gas without passing through a liquid state.