Question

Drinks remain hot or cold for a long time in a thermos flask because of the

• A. presence of air, which is a bad conductor of heat, in between the double walls
• B. silver coating on the inside of the double walls
• C. vacuum between the double walls
• D. combined effects of (b) and (c)

Answer 1

The correct option is D combined effects of (b) and (c)

Option:(d)