Hint: On the top of the mountain there is less pressure on the molecules.
According to Gay Loussac’s Law at constant volume, the pressure of a fixed amount of a gas varies directly with temperature.
So, when pressure is low the temperature is also kept lowered for processes to take place. When the graph is plotted between pressure and temperature, each line is called Isochore.
High temperature: Water boils at high temperatures at sea level because at sea level pressure is high. So, this option is incorrect.
Same temperature: According to the change in pressure, temperature also changes. So, this option is also wrong.
High pressure: On top of the mountain , the pressure is low. Hence, this option is not correct.
Low temperature: According to gay Loussac’s law, pressure varies directly with temperature so at high altitudes pressure is low hence the temp required for boiling the water is also low. So, this option is correct.
Our required Ans is ‘D’ that is low temperature. .
Some more laws are given to define relationships between gas constants.
Boyle’s law:- It states that at a constant temperature, the pressure of a fixed amount of gas varies inversely with volume.
Charles’ law:- It states that at constant pressure the volume of a fixed amount of gas is directly proportional to its absolute temperature.