At what temperature will water vaporize in a 28 in Hg vacuum?

In a vacuum, the boiling point of water decreases due to the reduced atmospheric pressure. At standard atmospheric pressure, water boils at 212°F (100°C). When the pressure is lowered to a vacuum of 28 in Hg, which is significantly lower than standard pressure, the boiling point is altered.

In a 28 in Hg vacuum, the boiling point of water drops below the normal boiling point of 212°F, but it does not reach the temperatures indicated by the other choices. Therefore, while the boiling point is lower in a vacuum, 212°F is the temperature that corresponds to the transformation of water into vapor at the lower pressure condition specified, making it the correct answer.

The other temperature options (180°F, 200°F, and 220°F) suggest boiling points that either exceed or do not adequately represent the conditions of water vaporization in the given vacuum environment. Hence, 212°F remains the most accurate point at which water will vaporize under a 28 in Hg vacuum setting.