Question

Which species has a normal boiling point closest to the normal boiling point of argon, Ar? (A) H2 (B) N2 (C) F2 (D) Cl and why

Answer 1

Argon is a gas so the closest boiling points would be the fluorine.Chlorine has a boiling point of -34.4 C. Argon has a boiling point of -185.7 C so fluorine has the closest to argon as its boiling point is -188.12 C.

Both argon and fluorine are non-polar (Ar because it is made of single atoms, F₂ because the electronegativity difference is 0.0 and the bond is covalent).

Both have London dispersion force drawing them together.

These two are isoelectronic so the London force should be the same. This is manifested in similar boiling temperatures.

boiling requires overcoming intermolecular forces of attraction. One such force is called "london dispersion forces" which is basically electrostatic forces of attraction caused by dipole moments in the molecules.

dipole moments are the result of differences in electronegativity. diatomic MONOelemental molecules like F2 have NO difference in electronegativity. So they would have no london dispersion forces to speak of.

Neither does Argon being that it's a monoatomic gas. 1 atom. so I would expect argon to have a very low boiling point because it has little to no intermolecular forces of attraction.