Question

According to the kinetic theory of gasses at absolute zero temperature

• A. Water freezes
• B. Liquid helium freezes
• C. Molecular motion stops
• D. Liquid hydrogen freezes

Answer 1

The correct option is C

Molecular motion stops

Kinetic theory of gases:

1. In the 19th century, the kinetic theory of gases was derived by James Clerk Maxwell and Ludwig Boltzmann. It illustrates the thermodynamic behavior of gases.
2. It describes that, gas is a large number of submicroscopic particles, all of which are in constant, rapid, random motion. The size of these particles is assumed to be much smaller as compared to the distance between them.
3. These particles go under elastic collisions among themselves and with the container wall.
4. This model is described for an ideal gas and assumes that the particles does not interact in any other way.It is known that the root mean square velocity of a particle is proportional to the absolute temperature. Also for zero absolute temperature, the velocity is also zero.
5. Mathematically the root mean square velocity is expressed as, $v_{rms}=\sqrt{\frac{3RT}{M}}$, where $R$ is the ideal gas constant, $T$ is the temperature of the gas and $M$ is the molecular mass of the gas.
6. Thus, due to the velocity being zero the whole system will come to rest. Therefore, the molecular motion will stop at absolute zero.

Hence, the correct option is (C).