Question

When a liquid in a closed container reaches a state of equilibrium with its vapor,
a. the number of molecules in the vapor state and the liquid state are equal
b. the number of molecules evaporating and condensing are equal

Answer 1

B. is obviously correct, since, for e.g., if one molecule evaporates and goes in the vapour state, according to your statement, another molecule condenses and comes to the liquid.

Answer 2

That's what I thought, but I wanted to make sure. Thanks!