Which substance has the highest melting point?

Write a note on Dipole-Induced Dipole forces.

The solid $NaCl$ is a bad conductor of electricity since:

What is the dependence of interaction energy on the distance $(r)$ between molecules for the following forces?
$(i)$ London forces
$(ii)$ Dipole-dipole forces (stationary)
$(iii)$ Dipole-induced dipole forces

What is the cause of metallic luster?

Which set of compounds in the following pairs of ionic compounds has the higher lattice energy?
$(i) \, KCl$ and $MgO$
$(ii) \, LiF$ and $LiBr$
$(iii) \, Mg_3N_2$ and $NaCl$