Q1: Which of the following is an example of cathodic protection of metals against corrosion ?

ANS:B - Galvanised iron

Galvanized iron is an example of cathodic protection of metals against corrosion. Cathodic protection is a technique used to prevent corrosion of metals by making them the cathode of an electrochemical cell. In the case of galvanized iron, it is protected by attaching sacrificial anodes (usually made of a more reactive metal like zinc) to the iron surface. When the galvanized iron comes into contact with an electrolyte (such as moisture), the sacrificial anode corrodes preferentially, providing cathodic protection to the iron substrate. This process helps to inhibit corrosion and extend the lifespan of the iron. Painted steel, case hardened steel, and lead-lined reactor are not examples of cathodic protection. Painting steel provides a barrier to moisture and oxygen, but it does not actively protect the metal against corrosion through cathodic protection mechanisms. Case hardening is a heat treatment process to increase the surface hardness of steel, while a lead-lined reactor is designed to contain hazardous materials rather than protect against corrosion.