Question

Arrange the following in order of their densities - ice, water, water vapour. Give proper justification

Answer 1

water has highest density since it's interparticle force of attraction is more than ice has more density than water vapour but less than water since it occupies air which has major volume at last is the water vapour since it has the least interparticle force of attraction

Answer 2

In case of solid ice, the hydrogen bonding gives rise to a cage like structure of water molecules. As a matter of fact, each water molecule is linked tetrahedrally to four water molecules.
Obviously, the molecules are not so closely packed as they are in the liquid state. When ice melts, this cage like structure collapses and the molecules come closer to each other. Thus, for the same mass of water, the volume decreases and hence density increases. Therefore, ice has lower density than water at 273 K. That is why ice floats on water. Same goes for water vapour, due to loosely bonded hydrogen and ibtermolecular bonding.