In which of the following molecules is the covalent bond most polar?

The standard molar enthalpy of vaporisation $(\Delta_{vap}H^{\circ})$ of $A, B$ and $C$ liquids is $23.3, 41$ and $29 \ kJ \ mol^{-1}$ respectively. The correct order of dipole-dipole attractive forces in these liquids is

Which of the following molecules has the maximum dipole moment?

Which of the following exhibits a dipole moment?

If $HCl$ were purely ionic,its expected dipole moment would be $6.12 \, D$. However,the experimental dipole moment is $1.03 \, D$. Calculate the percentage ionic character. (in $\%$)

The dipole-dipole interaction energy between polar molecules in the solid state will be proportional to ...... [if $r$ denotes the distance between polar molecules]