Two forms of solid carbon, diamond and graphite, differ in their physical properties due to the differences in their
(1) atomic numbers
(2) crystal structures
(3) isotopic abundances
(4) percent compositions

Answer; - Crystal structure Explanation; -Diamond and graphite are allotropes of carbon, they differ in physical properties. -In graphite, carbon atoms are covalently bonded to form sheets or what we call hexagonal layers, and these sheets are held together by weak inter-molecular forces called vander waal forces. This makes the layers to slide over each other , a property that makes graphite soft and slippery. -In Diamond, carbon atoms are bonded by strong covalent bonding forming a tetrahedron shaped solid of Diamond which makes it a very hard solid.

(1) atomic numbers(2) crystal structures(3) isotopic abundances(4) percent compositions