Which orbital is non directional?
They are non directional because they are spherical in shape and probability of finding electrons at a particular distance from the nucleus is same in all directions.
Ionic compounds usually have high melting and boiling points, Why?
Ionic compounds are formed by the transfer of electrons between two atoms that creates charge in them. The compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.