Question

Corresponding to the behaviour of the molecules of an ideal gas, which of the following statement is incorrect?

• A. A molecule may loose some part of its kinetic energy when it collides elastically with another molecule.
• B. There is a potential energy associated with the interaction between the molecules.
• C. Collisions between the molecules of a gas sample cannot change the internal energy of the gas sample.
• D. The speed of a molecule is not changed after collision with a wall of the container that is in thermodynamic equilibrium with the gas.

Answer 1

Answer: (B)

There is a potential energy associated with the interaction between the molecules.

Answer 2

According to KTG, for an ideal gas there exists no force of interaction between the molecules hence no potential energy can be defined associated with the interaction.

As for (1) sum of kinetic energies of two colliding molecules is conserved. Also total sum of KE of individual molecules is internal energy of the gas which is not altered by collisions between the molecules.

When a molecule collides with a wall it can exchange KE only if their temperatures are different. Collisions of the molecules with the wall are elastic if their temperatures are same.