Question

Which of the following water molecules, W, X, Y or Z can easily escape to form water vapour?

• A. W
• B. X
• C. Y
• D. Z

Answer 1

The correct option is B X

The phenomenon of change of a liquid into vapour at any temperature below its boiling point, is called evaporation.
Evaporation 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 underneath them. So, the molecule X present at the surface would escape the beaker first.