Q1. Anodising is:
A painting the metal surface
B forming a thick oxide layer on the metal surface Correct
C depositing a layer of zinc on the metal surface
D oiling the metal surface
Explanation
Anodising is an electrolytic process in which a controlled, thick oxide layer is formed on a metal surface, especially aluminium. This oxide coating protects the metal from corrosion and can also improve appearance. Painting only applies an external paint film; it does not create an oxide layer. Depositing zinc is galvanisation, a different anti-corrosion method. Oiling gives only a temporary protective film and is not the chemical or electrochemical surface treatment called anodising.