15. A substance that has a melting point of 1074 K conducts electricity when dissolved in water, but
does not conduct electricity in the solid phase. The
substance is most likely
A) an ionic solid
C) a metallic solid
B) a network solid
D) a molecular solid

Ionic solid.

Explanation:

Ionic solid dissociated into free ions capable of conducting electricity in aqueous solution. Ionic solids are also characterised by high melting point due to strong ionic bonds. No free ions or electrons to conduct electricity in solid form.

c. 75.7

i think that is the right