Question

When a container's metal lid is stuck, we put it in hot water for a while and then it becomes easier to open it. Why is it so?

• A. The hot water cleans it.
• B. The hot water will polish the metal.
• C. The heat expands the metal.
• D. The heat contracts the metal.

Answer 1

The correct option is C The heat expands the metal.

Metals expand on heating and on losing heat, they contract. So when we keep the container in hot water for a while, the metal lid expands and thus makes it easier for us to open it.