Question

Which of the following statement is correct?

• A. All substances expand on heating
• B. Heat energy flows from hot body to the cold body
• C. All substances contract on cooling
• D. All the above

Answer 1

The correct option is B

Heat energy flows from hot body to the cold body

In general, all substances expand on heating and contract on cooling but there are some substances, which in some temperature range behave exactly opposite to the normal i.e. they expand on cooling and contract on heating. One such substance is water. The anomalous properties of water are those where the behaviour of liquid water is quite different from what is found with other liquids. No other material is commonly found as solid, liquid and gas. But without external work heat always flows from hot body to cold body.