why can water dissolve salt but not a molecular substance like wax?

Answer 1

Water can dissolve salt because salt is an ionic compound that can easily dissociate in water.

Water cannot dissolve waxes because they are generally composed of hydrocarbon chains with fairly tight bonds that don't come apart in water.

But the simpler answer is - water can dissolve salt because salt is water soluble. Water can't dissolve wax because wax isn't.

Answer 2

because the force between the atoms is weak in ionic solids such as salt.