Is cl2 or F2 less volatile?

Cl2 is less volatile because it has more intermolecular forces and therefore has a higher boiling point.

Is this right?

2 answers

Yes, but you ought to think out what (at the same temperature), what the average KE does to heavier molecules...and that lessens the escape changes of the heavier molecule to break away from the surface.
Oh okay. We didn't learn that as of now. But I'll include that into my answer.