JEE Main 18 March 2021 Shift 2 Solved Paper

Covalent or network solid have very high melting point and they are insulators in their solid and molten form.
If a substance is an insulator in both solid and molten phases, then it cannot be ionic or metallic solid. If the melting point is higher, then it cannot be a molecular solid.
∴ It should be covalent network solid.