Question 9
A white solid melts at 993 °C, does not conduct electricity as a solid, and dissolves in water to give a solution that does conduct. What is its bonding?
The right answer is the one marked above.
Ionic. Every observation points the same way: a melting point in the hundreds means a lattice of strong attractions, and conducting when dissolved but not when solid is the signature of ions freed from a lattice.
A molecular covalent compound would melt far lower and would not conduct at all. A covalent lattice such as diamond melts high but has no ions, so its solution could not conduct either.