Question

If a gas expands at constant temperature indicates that:
A.The kinetic energy of molecules decreases
B.The pressure of the gas increases
C.The kinetic energy of molecules remains the same.
D.Number of the molecules of gas increases

Answer 1

Hint: Kinetic energy: kinetic energy is the energy possessed by an object by virtue of its motion i.e it is the energy used by the moving object.

Complete step by step answer:
The average kinetic energy of a gas molecule can be expressed by the given formula:
${ K.E= }\dfrac { 3 }{ 2 } { kT }$
where K.E = kinetic energy
k = Boltzmann constant
T = temperature
From here, we can say that the kinetic energy is directly proportional to the temperature.
When T = constant,so, K.E = constant
It means, If a gas expands at a constant temperature indicates that the kinetic energy of molecules remains the same.

The correct option is C.

Additional Information:
1.Kinetic theory of gases:
2.All gases are composed of very small particles called molecules.
3.Molecules are always in constant random motion.
4.There are no forces between the molecules.
5. Collisions between the molecules and the walls of the container are perfectly elastic.
6. The volume occupied by the molecules is negligible compared to the volume of the container.
7.The gravitational force has no effect on the molecules.
8. Molecules are assumed to obey Newton’s laws of motion.
9. Pressure experienced by walls of the container of the gases are due to the constant striking of molecules with the walls.

Note:
The possibility to make a mistake is that you may choose option B. But pressure has no effect on the kinetic energy of the gas molecules.