Question

why do we get dew on the surface of a cold drink bottle kept in open air?

Answer 1

we all know temperature of our surroundings is higher than the temperature of the cold drink.Air contains water molecules in  form of vapour.when molecules of water in air,during their motion strike the surface of bottle ;they lose their kinetic energy which lowers their temperature which converts them into droplets by condensation.

Answer 2

Condensation forms on any cold container because heat is transferred from water vapour in the air near the container to it, which warms the container and cools the vapour. The vapour turns back to liquid and condenses on the container surface.