CBSE Class 11 Physics Kinetic Theory of Gases Solved Examples

Ex.1 The mass of hydrogen molecules is 3.32 × 10^–27kg. If 10²³ hydrogen molecules strike a fixed wall of area 2 cm² at an angle 45º to the normal and rebound elastically with a speed of 10³m/s calculate the pressure exerted on the wall –
(A) 2.347 × 10³ N/m² (B) 23.47 × 10⁴ N/m² (C) 234.7 × 10³ N/m² (D) 23.47 × 10³ N/m²

Ex.2 Two ideal gases at temperature T₁ and T₂ are mixed. There is no loss of energy. If the masses of molecules of the two gases are m₁ and m₂ and number of their molecules are n1 and n2 respectively, the temperature of the mixture will be

Ex.3 The atomic weight of iodine is 127. A standing wave in a tube filled with iodine gas at 400 K has nodes that are 6.77cm apart when the frequency is 1000 vib/sec. iodine is
(A) Monoatomic (B)Diatomic (C) Triatomic (D) None of these

Ex.4 Certain perfect gas is found obey PV^3/2 = const. during adiabatic process. If such a gas at initial temperature T is adiabatically compressed to half the initial volume, in final temperature will be –

Ex.6 An air bubble of volume V0 is released by a fish at a depth h in a lake. The bubble rises to the surface. Assume constant temperature and standard atmospheric pressure above the lake. The volume of the bubble just before touching the surface will be (density) of water is r

Ex.7 Two gases occupy two containers A and B the gas in A, of volume 0.10m³, exerts a pressure of 1.40 MPa and that in B of volume 0.15 m³ exerts a pressure 0.7 MPa. The two containers are united by a tube of negligible volume and the gases are allowed to intermingle. Then it the temperature remains constant, the final pressure in the container will be (in MPa) –
(A) 0.70 (B) 0.98 (C) 1.40 (D) 2.10

Ex.8 If the pressure of a gas contained in a closed  vessel is increased by 0.5% when heated by 2ºC, then the initial temperature must be
(A) 127ºC (B) 273ºC (C) 400ºC (D) 673ºC

Ex.9 What is the degree of freedom of gas ? If at STP the velocity of sound in it is 330 m/sec and gas density = 1.3 mg/cm3.
(A) 2 (B) 3 (C) 5 (D) 4