Both coal and diamonds are forms of elemental carbon. coal is brittle while diamonds are considered to be the hardest of all substances known. what is the appropriate justification for this?

American scientist, linus pauling, was one of many scientists racing to discover the molecular structure of dna. pauling initially thought that the molecule was a triple helix. later, james watson and francis crick unveiled their double helix model, which turned out to be an accurate description of the molecule's shape. why did watson and crick succeed when pauling failed?