KTG exercise solution

Chapter 3: Kinetic Theory of Gases and Radiation
EXERCISES [PAGES 73 - 74]

Exercises | Q 1.1 | Page 73

Choose the correct option:
In an ideal gas, the molecules possess
1. only kinetic energy
2. both kinetic energy and potential energy
3. only potential energy
4. neither kinetic energy nor potential energy

SOLUTION
Only kinetic energy
Exercises | Q 1.2 | Page 73

Choose the correct option.
The mean free path λ of molecules is given by where n is the number of molecules per
unit volume and d is the diameter of the molecules.




Exercises | Q 1.3 | Page 73
Choose the correct option.
If the pressure of an ideal gas decreases by 10% isothermally, then its volume will
_______.
1. decrease by 9%
2. increase by 9%
3. decrease by 10%
4. increase by 11.11%

,SOLUTION




Exercises | Q 1.4 | Page 73

Choose the correct option.
If a = 0.72 and r = 0.24, then the value of tr is
1. 0.02
2. 0.04
3. 0.4
4. 0.2

SOLUTION
0.04
Exercises | Q 1.5 | Page 73
Choose the correct option.
The ratio of emissive power of perfect blackbody at 1327°C and 527°C is
1. 4:1
2. 16:1
3. 2:1
4. 8:1

SOLUTION
16:1
Exercises | Q 2.1 | Page 73

Answer in brief:
What will happen to the mean square speed of the molecules of a gas if the
temperature of the gas increases?

, SOLUTION
If the temperature of a gas increases, the mean square speed of the molecules of the
gas will increase in the same proportion.
Exercises | Q 2.2 | Page 73

Answer in brief:
On what factors do the degrees of freedom depend?

SOLUTION
The degrees of freedom depends upon
(i) the number of atoms forming a molecule
(ii) the structure of the molecule
(iii) the temperature of the gas.
Exercises | Q 2.3 | Page 73

Answer in brief:
Write ideal gas equation for a mass of 7 g of nitrogen gas.

SOLUTION




Exercises | Q 2.4 | Page 73

If the density of oxygen is 1.44 kg/m3 at a pressure of 105 N/m2, find the root mean
square velocity of oxygen molecules.

SOLUTION