Answer:
Water has the strongest inter-molecular forces.
Step-by-step explanation:
As given that water and ammonia both are polar however water is liquid and ammonia is a gas at room temperature.
Let us understand the difference between solid, liquid and gas.
The three states differ from each other due to
a) inter-molecular forces of attraction (the force of attraction between two molecules of same or different substance).
b) the thermal energy of molecules.
In case of solids the inter-molecular forces are maximum and the thermal energy is least. So the molecules are held strong with each other and does not move here and there.
In case of liquid and gas, the inter-molecular forces of attraction are stronger in liquid as compared to gas while thermal energy of gas molecules is more.
In water, the oxygen atom is more electro-negative than nitrogen of ammonia. This makes water molecular more polar.