i) Colouring with (b) water colours.
(ii) Writing on paper with (b) ink pen.
Explanation: Evaporation is crucial for watercolours to dry and set on paper, as they contain water that needs to evaporate to leave behind the pigment. Ink pens also rely on evaporation to dry the ink, whereas crayons and pencil colours are solid and do not involve evaporation in their application.