Molecules in a sample of NH3 (l) are held closely together by intermolecular forces

(1) existing between ions (2) existing between electrons (3) caused by different numbers of neutrons (4) caused by unequal charge distribution

Molecules in a sample of NH3 (l) are held closely together by intermolecular forces existing between ions. The answer is number 1. NH3 is governed by hydrogen bonding. Hydrogen bonding is the bonding between an H atom and the element that it combines with.