Step-by-step explanation:
A rate of reaction where rate of forward reaction is equal to rate of backward reaction is known as a reversible reaction.
When we boil water then molecules of water start to move from their initial position. As a result, bond between water molecules break and the start to collide rapidly with each other.
This leads to increase in kinetic energy of molecules. Hence, molecules change into vapor state.
Whereas when we cool these vapors then extra energy is released by the vapors. As a result, decrease in kinetic energy of vapor molecules occur due to which it changes into liquid state.
So, when water is boiled then it changes into vapors and when water vapors condense the it changes into liquid state.