Question

When water in an open vessel is taken to hill top and heated it starts boiling at?

Answer 1

The higher the pressure,  the higher boiling point of water. At lower the pressure, the boiling point of water comes down. So, the  lower pressure inreases the boiling resulting more evaporation. As we go higher in altitude, the atmospheric pressure decreases. This results in decreasing the boiling point at higher altitude and increase in boiling of water.