Solution:
(a) (i) In o-nitrophenol there is intramolecular hydrogen bonding due to which it is more steam volatile. In p-nitrophenol there is intermolecular hydrogen bonding which holds molecules together more strongly making it less steam volatile.
(ii) Tertiary cation and strong base Favours elimination reaction. t-butyl cation is formed as intermediate in this reaction. As methoxide ion is a strong base it favors elimination giving 2-methoxy as major product.
(b)
(c) Phenol is an unsaturated aromatic alcohol, while ethanol is saturated aliphatic alcohol. Ethanol reacts with triodomethane (iodoform test) and forms yellow precipitate, while phenol does not give this test. Phenol has benzene ring it under goes diazo coupling reaction, while ethanol doesn't give this test.