Consider the molecules HF and HCl. The electronegativities of the atoms involved are H, 2.1; Cl, 3.0; F, 4.0.

(a) Which of the two molecules is more polar? Explain your answer.

(b) For which substance are the dipole–dipole attractions between the molecules stronger? Explain your answer.

(c) Which gas would, upon cooling, liquefy first? Explain your answer. Also, indicate which compound would have the higher boiling point based on your answer.

(d) Do both molecules also experience London forces of attraction? If yes, which would have the greater London forces?