Question

At high altitudes, the boiling of water takes place below ${100}^{o}C$ because :

• A. the atmospheric pressure is low
• B. the temperature is low
• C. the atmospheric pressure is high
• D. none of the above

Answer 1

The correct option is A the atmospheric pressure is low

At high altitudes, the boiling of water takes place below ${100}^{o}C$ because the atmospheric pressure is low. The boiling occurs at lower temperature than boiling point if the atmospheric pressure is lower than 76 cm Hg.
At high altitude, the external pressure on the water is decreases, therefore, it will take less energy to break the water molecules free from their bonded energy. If it takes less energy, then it will take less heat, as this is the energy we are introducing. If less heat is required, then less temperature is required, then the water will boil at a lower temperature.