• Diamond is a crystalline solid of non-metal Carbon and it has covalent bonding throughout the crystal. Between two adjacent atoms of the crystal there is a strong and directional interaction which results in a covalent bond which helps the atoms to held strongly at their positions. Therefore resulting in a very high melting point which indicates that diamond is a network solid.

The network structure of diamond

• The other 3 options (i) SO₂ (Solid) (ii) I₂ and (iv) H₂O (Ice) are examples of molecular crystalline solids

• in which SO₂ (Solid) is a type of polar molecular solid (strong dipole-dipole interaction b/w S and O results in stronger polar covalent bonds).

• I₂ can be classified as non-polar molecular solid (formed by weakest dispersion force, London force due to temporary induced dipole-dipole interaction.

• And at last H₂O (Ice) is hydrogen-bonded molecular solid (polar covalent strong interaction b/w H and O reinforces the formation of hydrogen bond.