Question

answer (2) question

Answer 1

The brownish is non-other but Rust.
The Iron got rusted after coming in contact with moisture in the atmosphere.

4Fe(s) + 3O2(g) ———> 2Fe2O3(s)[Fe2O3 is Rust].

It can be prevented by galvanising or painting Iron or rushing it with a sand paper.

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Answer 2

Railings and Windows are made up of iron and since iron is a metal it RUSTS.

And what you use as a brownish layer is the rust of iron...

For its prevention we can use OIL , GREECE , and PAINTS.....

HOPE IT HELPS!!!!!!