Q.Why pressure Cooker is used for cooking food on hills?

On hills low atmospheric pressure lowers water's boiling point, so a pressure cooker is used to raise the internal pressure and hence the boiling point, cooking food properly.

A liquid boils when its vapour pressure becomes equal to the external (atmospheric) pressure. Therefore, the lower the external pressure, the lower the boiling point of the liquid.

On hills (high altitude), the atmospheric pressure is much lower than at sea level. As a result, water boils at a temperature well below 100 degree C. At this lower temperature the food does not receive enough heat, so it cooks slowly and often remains uncooked.

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