Final answer:
Each ammonia molecule (NH3) can, on average, form two hydrogen bonds at a time with other NH3 molecules due to one lone pair on nitrogen which can act as a hydrogen bond acceptor, and three hydrogen atoms act as donors.
Step-by-step explanation:
Ammonia, NH3, has the ability to form hydrogen bonds due to its polar nature and the presence of hydrogen atoms bound to a highly electronegative atom, which is nitrogen in this case. Each NH3 molecule can theoretically form one hydrogen bond through its nitrogen atom, as nitrogen has a lone pair that can act as a hydrogen bond acceptor. Additionally, each hydrogen atom in NH3 can be considered a hydrogen bond donor. On average, pure liquid NH3 can form two hydrogen bonds at a time with other NH3 molecules, similar to hydrogen fluoride (HF).