(a) Give one physical property of (i) diamond; (ii) graphite (b) Give two uses of diamond (c) evidence that shows that both graphite and diamond are allotro...

Answer Details

(a) Physical property

• (i) Diamond: it is extremely hard (the hardest natural substance) and transparent; it does not conduct electricity.
• (ii) Graphite: it is soft, slippery and greyish-black (opaque); it conducts electricity.

(b) Two uses of diamond: for making cutting and drilling tools (e.g. glass cutters and rock drills) and as an abrasive for grinding and polishing; it is also used in jewellery.

(c) Evidence that graphite and diamond are allotropes of carbon: both substances are composed of carbon only, and when each is completely burnt in excess oxygen the only product formed is carbon dioxide (in the same proportion). Producing the same single product on combustion shows that both are simply different physical forms of the same element, carbon, which is what allotropy means.