(a) Galvanised iron refers to iron being coated with zinc by plunging it into molten zinc, or by electrolysis. Because zinc is more reactive than iron, it reacts first and prevents iron from rusting.
(b) Passive iron refers to iron oxide that is formed by the reaction of iron with nitric acid. When nitric acid reacts with iron, it forms a protective oxide layer over it and makes iron passive (inert) to further reactions.