A sample of water vapor condenses to form liquid water. What change in water allows this to happen?

Condensation is the process of water vapor condensing into liquid water.

Explanation:

"Water condenses on a can of cold soda. Water vapor in the air reaches its dew point as it cools in the air around the can, forming liquid drops of water. Condensation is the process where water vapor becomes liquid. It is the reverse of evaporation, where liquid water becomes a vapor." -National Geographic"

i believe that it is a exoplanet

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.