Explain how the strongest type of intermolecular force in liquid HF arises

The fairly positive hydrogen on one HF molecule will be attracted to one of these lone pairs on a nearby HF molecule. This is a hydrogen bond. Hydrogen bonds are attractions between a δ+ hydrogen on one molecule and a lone pair on a very electronegative atom (N, O or F) on another molecule.

Explanation:

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

that tool would be a compass