Boiling points of three substances X,Y and Z are in the order TX > TY > TZ.  Identify X,Y and Z

Boiling point H2O > HF More number of H - bonds in water than in HF in liquid state. In vapour state HF is associated due to H - bond but no association in water vapour.Boiling point HF > NH3Electronegativity of F > N and size of F < N, H - bond is stronger in HF than in NH3.