Question

The boiling point of water is low at high altitude. Explain:

Answer 1

Hint: We know that the boiling point is a physical property of a compound. The boiling point is defined as the temperature at which a compound's vapor pressure reaches the pressure of the atmosphere. At higher altitude, atmospheric pressure is lower.

Complete step by step answer:
One of the scientific "truth" we learn early in school is the boiling point of water. All acknowledge that ${\rm{100}}{\;^{\rm{o}}}{\rm{C}}$ is the boiling point of water. The reality, however, is valid at sea level and is subject to change under various conditions. A change in altitude is one of those factors. Air pressure will decrease at higher altitudes. The higher we climb into the atmosphere, there is literally less air bearing down on us. Then why is the boiling point of water influenced by this? Let’s discuss in detail.
You need to add energy in the form of heat to boil water. They start to break the bonds binding them together as energy is transferred to the water molecules. As soon as its inner vapor pressure approaches the pressure exerted by the atmosphere on it, the water will boil or turn to vapor. Bubbles start to form as that happens and the water boils.
It requires less energy to get water to the boiling point if the atmospheric pressure is lower, or at a higher altitude. Hence, we can say that the boiling point of water is low at high altitude.

Note:
As we know, Earth’s atmosphere has a huge reservoir of gas, due to the earth’s gravity exerts pressure on the Earth's surface. This atmospheric pressure is measured by a simple instrument called ‘mercury barometer’.