Statement I: Cooking time is reduced in a pressure cooker.
Statement II: The boiling point of water inside a pressure cooker is higher than its normal boiling point.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I
A liquid boils at the temperature at which its vapour pressure equals the external pressure on it.
Statement I: Cooking time is reduced in a pressure cooker. — True. Food in a pressure cooker cooks at a higher temperature than in an open pan, and most chemical reactions, including those that cook food, go faster as the temperature rises.
Statement II: The boiling point of water inside a pressure cooker is higher than its normal boiling point. — True. The closed cooker traps the steam, so the pressure on the water rises above 1 atm. The vapour pressure of water must now rise to this higher pressure before the water boils, so it boils only above 373.15 K, its boiling point at 1 atm.
Why Statement II explains Statement I?
In an open pan the water, and the food in it, cannot get hotter than about 373 K, because the water boils away at that temperature.
In the cooker the water stays liquid up to a higher boiling point, so the food is cooked at this higher temperature. The cooking reactions are faster, and the cooking time is shorter.
NCERT (2026-27 edition):
1.6.2 Elevation of Boiling Point – “The vapour pressure of a liquid increases with increase of temperature. It boils at the temperature at which its vapour pressure is equal to the atmospheric pressure. For example, water boils at 373.15 K (100° C) because at this temperature the vapour pressure of water is 1.013 bar (1 atmosphere).”
3.4 Temperature Dependence of the Rate of a Reaction – “Most of the chemical reactions are accelerated by increase in temperature.”