Which of the following will increases the boiling point of water?

I. Taking it to a high altitude
II. Dissolving a salt into it
III. Heating it in a sealed flask
IV. Increasing the rate of heat supply

.

A. I only
B. III & IV only
C. II & III only
D. II only

Correct Answer:

Option D – II only

Explanation

At elevated altitudes, any cooking that involves boiling or steaming generally requires compensation for lower temperatures because the boiling point of water is lower at higher altitudes due to the decreased atmospheric pressure.

As pressure increases, the energy required to boil a liquid increases because boiling point is the point where the vapour pressure equals or exceeds the atmospheric pressure.

For this reason, adding a solute to the liquid (impurituies) will create stronger bonds between molecules, raising the solution’s boiling point without increasing pressure.