1. Answer any three parts

State the assumptions of kinetic theory for ideal gases.

What is Joule-Thomson effect? Why is it also called is enthalpic effect? Justify your answer.

A quantity of dry air 1.4) at 15°C is adiabatically compressed to half its volume. Calculate the final temperature.

Show that entropy S and thermodynamic probability W for a completely ordered system is S =kln W.

2. Show that a gaseous system can be characterised by the relation

dv/v BdT-k dp

where k is isothermal compressibility and B is isobaric expansivity.

OR

Define entropy. Calculate the change in entropy when two gases kept in separate containers are allowed to mix.

3. Attempt any two parts:

What is an adiabatic process? Show that the work done during an adiabatic process is

W

State Kelvin-Planck and Clausius statements of second law of thermodynamics. Show that these two statements are equivalent.

Write Van der Waals equation of state for a real gas. Show that the Boyle's temperature is related to critical temperature through the relation TB 3·375 Tc

4. What is Gibbs paradox? Derive Sackur-Tetrode equation for the entropy of an ideal monoatomic gas and show how it is free from Gibbs paradox.

OR

What is adiabatic demagnetisation Describe an experimental set-up for production of low temperature using this process.

The energy distribution of black body radiation according to Planck's law is given by

<img src='./qimages/10405-5a.jpg'>

Obtain the expression for Stefan-Boltzmann constant.

Starting from the relation

<img src='./qimages/10405-5b.jpg'>

obtain an expression for adiabatic lapse rate. What is its physical significance?

OR

Derive the Clausius-Clapeyron equation. Calculate the depression of the melting point of ice 80 cal per atmospheric increase of pressure, if the ratio of the densities of ice and water at 0°C is 10/11