State the reasons for

(a) Use of diamond - as an item of jewellery.

(b) Use of graphite -

(i) as a lubricant for heated machine parts,

(ii) as a lining for crucibles used in manufacture of high grade steel

(iii) as an electrode in electroplating.

State in brief the transformation of vegetable matter to different types of coal varying in carbon content. State two uses each of

(a) coal

(b) coke

(c) lampblack or soot

Carbon dioxide occurs both in the free state and in the combined state. State three methods how carbon dioxide is added to the atmosphere.

In the laboratory preparation of carbon dioxide by action of a dilute acid on a metallic carbonate give -

(a) A balanced equation for the preparation

(b) A reason for

(i) use of a washer bottle containing conc. H₂SO₄ in the preparation

(ii) Not collecting the prepared gas over water

(iii) Not using dilute sulphuric acid as a reactant in the preparation.