A pressure cooker allows food to be cooked under high pressure. Why is this useful?

• A. It increases the boiling point of water, allowing food to cook faster at higher temperatures.
• B. It prevents water from evaporating, so food remains dry during cooking.
• C. It adds extra oxygen to the food, making it cook more quickly.
• D. It decreases the boiling point of water, so food cooks at lower temperatures.

Answer: (A)

Verified step by step guidance

1. Understand that the boiling point of a liquid depends on the pressure exerted on it. At higher pressures, the boiling point increases, and at lower pressures, it decreases.
2. Recognize that a pressure cooker is a sealed container that traps steam, increasing the pressure inside the cooker above atmospheric pressure.
3. Apply the concept that increasing pressure inside the cooker raises the boiling point of water above 100°C, allowing the water and steam to reach higher temperatures without boiling away.
4. Realize that cooking food at higher temperatures speeds up the chemical reactions involved in cooking, thus reducing the cooking time.
5. Conclude that the main usefulness of a pressure cooker is that it increases the boiling point of water, enabling faster cooking at higher temperatures.