Compare the boiling points?

Question

Compare the boiling points at low and high altitudes?

Answer 1

A liquid will boil when its vapor pressure equals the pressure above the liquid. At a given temperature, a liquid's vapor pressure is constant.
If one wants to make a liquid boil at a lower temperature, one must lower the pressure above the liquid.

At higher altitudes, the air pressure is generally lower. At sea level, the pressure is usually about 1 atm (atmosphere), and at this pressure pure water boils at 100 degrees C. If one goes up into the mountains where the air pressure is lower, water will boil at a lower temperature than 100 degrees.

Answer 2

Pressure acting on the fluid decreases at high altitudes as air density decreases. Accordingly, the boiling point should also decrease.