Classify the following as a physical or a chemical change :
(a) Drying of wet clothes
(b) Manufacture of salt from sea water.
(c) Butter getting rancid
(d) Boiling of water
(e) Burning of paper
(f) Melting of wax
(g) Burning of coal
Classify the following as chemical or physical changes: Boiling of water to form steam.