Question

we are also aware of the fact that water vapour Deposits on a mirror if we breath out on it

Answer 1

When we breath in, we inhale oxygen and water vapours in the form of moisture.When we breath out the moisture is also brought back.

Answer 2

Explanation:

Our warm moist breath leaves a deposit of fine dew like particles on the glass - the glass turns misty. This is because of condensation. The air that we breathe has water vapour. When we blow it out and it comes into contact with a cool surface, the vapour condenses into water droplets.