Differentiate between rubbers and plastics on the basis of intermolecular forces.

Explanation

Natural rubber is cis-polyisoprene formed by polymerisation of isoprene i.e., 2-methyl-1, 3-butadiene. Because of this configuration about the double bonds, the polymer chains donot come close. Therefor, the only attractive forces which are van der Waal's forces, are quite weak

Plastics are basically synthetic or man made polymers. These include both addition polymers like polyethene, polyvinyl chloride, polystyrene etc. and also condensation polymers like nylon. The attactive forces are comparatively strong since these are dipolar forces such as intermolecular hydrogen bonding. They therefore, generally hard as compared to natural rubber. For more details, consult section 5, 6 and 7