Question

Compared with ionic compounds, molecular compounds


have lower melting points


have higher boiling points


are brittle


are harder

Answer 1

Only "have lower melting points" is correct.

Reason: Ionic compounds form strong electrostatic lattices, so they require much more energy to melt or boil than molecular (covalent) substances, which are held together by weaker intermolecular forces. Ionic solids are also typically hard and brittle, whereas molecular solids are generally softer (not harder) and have lower boiling points (not higher).