Question

A thermos flask can keep hot liquids hot for several hours but cannot keep cold liquids cold.

• A. True
• B. False

Answer 1

The correct option is A True

1. The air between the two walls is sucked out to create a vacuum.
2. It keeps hot as hot by not allowing heat energy to escape.
3. The outer surface of its inner wall and the inner surface of its outer wall are silvered which prevents heat transfer due to radiation.
4. The inner double-walled glass vessel and vacuum prevents heat loss by conduction.

Hence, the given statement is true.