Question

Water boils at a lower temperature at high altitudes, because ______.

• A. the air pressure is less
• B. outside temperature is less
• C. latent heat is less
• D. none of the above

Answer 1

The correct option is A the air pressure is less

The boiling point of water is lower at higher altitudes due to the decreased atmospheric pressure. A liquid boils when its vapour pressure exceeds the local total pressure. As the atmospheric pressure drops, the Vapour pressure increases more than the local pressure at an even lower temperature. At sea level water boils at 100°C. For each 500 ft increase in elevation, the boiling point of water is lowered by approximately 0.5°C.