What is the effect of lower atmospheric pressure on mountain peaks on the boiling point and evaporation of water?

Correct answer: The boiling point decreases and evaporation can occur more readily even at a lower temperature

Correct answer: B. A liquid boils when its vapour pressure becomes equal to the pressure exerted by the surrounding atmosphere. At high mountain elevations, atmospheric pressure is lower, so water needs a lower temperature for its vapour pressure to match the external pressure. Therefore, the boiling point decreases. Lower pressure also reduces the opposing pressure at the water surface, so molecules can escape more readily; evaporation may occur more easily at a given temperature, although the actual rate also depends on temperature, humidity, wind and exposed area. Option A reverses the pressure relationship. Option C ignores the physical effect of pressure. Option D is wrong because low pressure does not by itself freeze water. Remember: lower external pressure means lower boiling temperature, not freezing.