Question

A glass full of hot milk is poured on the table . It begins to cool gradually. Which of the following is incorrect?

• A. The rate of cooling is constant till milk attains the temperature of the surrounding
• B. The temperature of milk falls of exponentially with time
• C. While cooling there is a flow of heat from milk to the surrounding as well as from surrounding to the milk but the net flow of heat is from milk to the surrounding and that is why it cools.
• D. All three phenomenon, conduction, convection and radiation are responsible for the loss of heat from milk to the surroundings.

Answer 1

Answer: (B), (C), (D)

The correct options are
B The temperature of milk falls of exponentially with time
C While cooling there is a flow of heat from milk to the surrounding as well as from surrounding to the milk but the net flow of heat is from milk to the surrounding and that is why it cools.
D All three phenomenon, conduction, convection and radiation are responsible for the loss of heat from milk to the surroundings.

The heat from hot milk spread on the table is transferred to the surroundings by conduction, convection and radiation. According to Newton's law of cooling the temperature of milk falls exponentially with time.

Hence, option $\left(A\right)$ is correct.