c) How can corrosion be prevented ?

Explanation

1) When some metals are exposed to moisture, acids, etc. they tarnish due to the formation of respective metal oxide on their surface. The process is called corrosion.
2) i) Tarnishing on silver ware.
`4Ag+2H_(2)S+O_(2)rarr 2Ag_(2)S+2H_(2)O`
(Black coating (due to `Ag_(2)S`) forms on silver articles)
ii) Corrosion of copper.
`2Cu+O_(2)rarr 2CuO.`
(Treen coating (due to `CuO`) on copper)
3) Corrosion is the oxidative deterioration of a metal.
4) Corrosion causes damage to car bodies, bridges, iron railings, ships, etc.
5) And to all other objects that are made of metals are effected by corrosion.
6) Especially corrosion of iron is a serious problem.
7) Corrosion can be prevented or minimized by shielding the metal surface from oxygen and moisture.
8) It can be can be prevented by painting oiling, greasing, galvanizing, chrome plating or making alloys.
9) Alloying is also a very good method of improving properties of metal.
Eg : steel,bronze,brass.