Awhite substance melts with some decomposition at 730oc. as a solid it does not conduct electricity, but it dissolves in water to form a conducting solution. with explanation, which type of solid might the substance be?

Ionic solid

Explanation:

Ionic solids -

These are the type of solids , which is composed of ions , which are bond by very strong electrostatic force of attraction , are referred to as ionic solids.

And due to very strong force of attraction between the ions , they generally have very high melting point.

When the solid is dissolved in water , the ions gets separate out , and these free ions are capable to conduct electricity , and hence they are very good conductor in molten form , and are insulator in solid form.

Hence , from the given information of the question ,

The correct term is ionic solids.