Question

Among the given water molecules W, X, Y and Z, which of the following can easily escape to form water vapour?

Answer 1

The phenomenon of change of a liquid into vapour at any temperature below its boiling point is called evaporation.
It is a surface phenomenon.
Molecules at the surface have higher energy than the molecules at lower levels in the beaker. This enables them to break free and turn into water vapour faster than the molecules present in the bulk. So, the molecule X at the surface would first escape the beaker.