On top of a mountain, the boiling point of water is?

The boiling point of water is indeed lower at higher elevations, such as on top of a mountain, because atmospheric pressure is lower in these areas. At sea level, atmospheric pressure is at its highest, which allows water to reach its boiling point at 100 degrees Celsius (212 degrees Fahrenheit). However, as altitude increases, the atmospheric pressure decreases, which in turn lowers the boiling point of water.

This phenomenon occurs because boiling happens when the vapor pressure of the liquid equals the surrounding atmospheric pressure. With reduced pressure at higher altitudes, water requires a lower temperature to reach a vapor pressure that is equal to the surrounding pressure, causing it to boil at temperatures below 100 degrees Celsius.

Understanding this concept is essential for various applications, such as cooking at high elevations or performing scientific experiments that involve boiling water. This principle is why the correct answer emphasizes that the boiling point is lower due to the lower atmospheric pressure found on mountains.