Question

Air is a bad conductor of heat because:
(A) its molecules are it continuous contact with each other
(B) its molecules are not in continuous contact with each other
(C) its molecule absorbs all the heat
(D) its molecules are moving randomly due to Brownian motion

Answer 1

Hint: The heat is transferred from hot body to cold body by means of three types. They are conduction, convection and radiation. The heat transfer is different for different states like solid, liquid and gas. The heat transfer is done by the atoms and molecules of the objects.

Complete step by step solution
Generally, heat is transferred from one part of the body to another part of the same body or between the two touching objects. This type of heat transfer is called conduction. In conduction, the heat is transferred from hot body to cold body through molecular movement and molecular vibration. In solid material, the molecules are closely arranged so that the molecular vibration between the molecules is more efficient and transfers more heat.

In liquids, the molecules are arranged in some random distance. So, the heat transfer is not so efficient like the heat transfer in solid material. When the molecules are arranged in random distance, the molecular vibration does not have that much efficiency so the heat transfer is less when compared to solids.

But in gas, the space between the molecules is high. So, the heat transfer in gas is very less when compared to heat transfer in liquids. Solids are better conductors than liquids, liquids are good conductors than gas. So, the air is a bad conductor of heat.

Hence, the option (B) is correct.

Note: The maximum heat is transferred by conduction. If the heat transfer occurs in fluids, the type of heat transfer is convection. In convection the heat transfer is very poor because of the molecular arrangement of the molecules and its molecules are not in continuous contact with each other.