A vapour is said to be saturated when?

A.

more molecules return to the liquid than leave it

B.

a dynamic equilibrium exists between the liquid molecules and the vapour molecules at a given temperature

C.

the vapour pressure is atmospheric

D.

the temperature of the vapour varies

E.

all molecules are moving with the same speed

Correct answer is B

A vapor saturated is said to be in a dynamic equilibrium with its own liquid