Concept:Electrovalent compounds are ionic compounds formed by the transfer of electrons from one atom to another.
Explanation:In the solid state, the ions in an electrovalent compound are held tightly in a rigid lattice.
These ions are not free to move, so the solid does not conduct electricity.
When dissolved in a polar solvent such as water, the lattice is broken apart and the ions become free to move.
This allows the solution to conduct electricity.
Electrovalent compounds generally have high melting and boiling points because of strong electrostatic forces between ions.
They do not contain mobile electrons, so they are not electrical conductors in the solid state.
Thus, the characteristic property given in the options is that electrovalent compounds normally dissolve in polar solvents.
Answer:D. dissolve in polar solvent