Question

What happens to the boiling point of water in a container when the container is completely closed by a lid?

(a) Increases

(b) Decreases

(c) Remains same

(d) Boiling point is characteristic of a substance

I got this question by my college director while I was bunking the class.

This intriguing question originated from Thermal Properties of Matter topic in division Thermal Properties of Matter of Physics – Class 11

Answer 1

Correct answer is (a) Increases

Best explanation: Boiling occurs when vapour pressure of liquid is the same as atmospheric pressure. The vapour pressure increases with increase in temperature. So when temperature has been increased sufficiently boiling starts. But with increase in pressure at higher vapour pressure has to be reached which is obtained by increasing temperature and therefore we say boiling point increases.