The boiling points of water and 2-methyl-2-propanol are 100 °c and 82.2 °c respectively. which liquid has a lower vapor pressure at a given temperature?

When a liquid is boiled, the vapour pressure exerted by that liquid increases with increasing temperature. As the vapour pressure of that liquid becomes equal to the surrounding pressure, then vaporization occurs.

Since in this case, the propanol has a lower boiling point, therefore this means that it has higher vapour pressure at this pressure than water.

SO the liquid with lower vapour pressure is water.

water

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.