Write 'true' or 'false' against the following statements :
(a) Carbon constitutes 0.03% of the earth's crust.
(b) Graphite is the purest form of carbon.
(c) Coloured diamonds are costlier than colourless and transparent diamonds.
(d) Graphite has layers of hexagonal carbon bondings.
(e) Diamond is insoluble in all solvents.