Question

Water boils at a lower temperature on the hills because _______________.

• A. Temperature is low on the hills
• B. There is less oxygen on the hills
• C. There is less pollution on the hills
• D. There is less air pressure on the hills

Answer 1

The correct option is D There is less air pressure on the hills

• 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. At high altitudes the local air pressure is lower than it is at sea level.
• Thus, the lower pressure allows the liquid to boil at a lower temperature.