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