Solid $PCl_5$ exists as $:$

Dipole-induced dipole interactions are present between which of the following pairs?

Diamond is extremely hard whereas graphite is soft. This is because

Lattice enthalpy for $NaCl$ is $+788 \ kJ \ mol^{-1}$ and $\Delta H_{\text{hyd}}^{\circ} = -784 \ kJ \ mol^{-1}$. The enthalpy of solution of $NaCl$ is:

What is lattice enthalpy? Give an example.

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