What is the valency of iron in the products formed
(a) When iron is exposed to humid air for a long time?
(b) When red hot iron is made to react with steam?

Explanation

(a) When Fe is exposed to humid air for a long period of time , it gets rusted.
`"Rust" " " : " " Fe_(2)O_(3).xxH_(2)O`
Valency of Fe is '3'
`3Fe+underset(" steam")(4H_(2)O)tounderset(("ferrose ferric oxide"))(Fe_(3)O_(4)+4H_(2))`
`(Fe_(3)O_(4)` is a mixed oxide that is `FeO+Fe_(2)O_(3))`
(Valency of iron in `Fe_(3)O_(4) ` is 2 as well 3)