Which compound has the highest melting point?
silicon carbide (sic), a network solid
octane (c8h18), a molecular compound
carbon dioxide (co2), a common gas
water (h2o)

silicon carbide (SiC), a network solid

Explanation:

SiC has a giant network of covalent structure which takes a lot of energy to break than just a single covalent bond. In the network there are many Si and C atoms. All the atoms in the network are linked to each other by strong covalent bonds. SiC forms a lattice structure, in which both the Si and C atoms are sp³ hybridized. In the SiC crystal lattice the smallest unit is a tetrahedron of a central Si atom surrounded by four C atoms or a central C atom surrounded by four Si atoms.