Explain why the surfaces of some metals become dull when exposed to air for sometime.

Give reasons for the following : (i) Carbonate and sulphide ores are converted into oxides before reduction. (ii) Aluminium is rendered passive when it is dipped in conc. HNO_(3) (iii) Nonmetals do not displace hydrogen from acids. (iv) An aqueous solution of CuSO_(4) cannot be stored in an iron vessel. (v) The surface of some metals become dull when left exposed to air for a long time.

Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.

(a) Give reasonwhy copper is used to make hot water tanksbut steel (an alloy of iron) is not. (b). Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.

(a) Which of the following metals would give hydrogen when added to dilute hydrochloride acid (i) iron (ii) copper (iii) magnesium ? (b) Explain why do surfaces of some metals acquire a dull appearance when exposed to air for a long time.

Why do some metals acquire a dull appearance on exposure to air for a long time ?

Crystals of ferrous sulphate when exposed to air become

The red or Orange coating that forms on the surface of iron when exposed to air and moisture for some time is called

Name the chemical compounds formed on the surface of silver, copper and iron metals when exposed for sometime to atmosphere.

What happens to the crystals of washing soda when exposed to air ?