Question

Explain why iron pipe for carring water are coated in with zinc

Answer 1

iron pipe are galvanized to prevent it from rusting.

Answer 2

Its is because zinc cannot rust like iron.
The process of covering iron with zinc to prevent rusting is galvanising.
Zinc is used as a sacrificial metal in this case as it is more reactive than iron so it gets oxides first, which takes a long while, before it is fully diminished and the iron beneath gets rusted.