# Physics: Thermodynamics

##### 21. Question

A thermally insulted vessel contains 150 g of water at 0°C. Then the air from the vessel is pumped out adiabatically. A fraction of water turns into ice and the rest evaporates at 0°C itself. The mass of evaporated water will be closed to: (Latent heat of vaporization of water = 2.10 × 10^{6} J kg^{–1} and Latent heat of Fusion of water = 3.36 × 10^{5} J kg^{–1} )

Answer

##### 22. Question

Following figure shows two processes A and B for a gas. If ΔQ_{A} and ΔQ_{B} are the amount of heat absorbed by the system in two cases, and ΔU_{A} and ΔU_{B} are changes in internal energies, respectively, then:

Answer

##### 23. Question

n moles of an ideal gas with constant volume heat capacity C_{V} undergoes an isobaric expansion by a certain volume. The ratio of the work done in the process, to the heat supplied is:

Answer

##### 24. Question

One mole of an ideal gas passes through a process where pressure and volume obey the relation P = P_{0}[1 – 1/2 x (V_{0}/V)^{2}] Here P_{0} and V_{0} are constants. Calculate the charge in the

temperature of the gas if its volume changes from V_{0} to 2V_{0}.

Answer

##### 25. Question

A cylinder with fixed capacity of 67.2 lit contains helium gas at STP. The amount of heat needed to raise the temperature of the gas by 20°C is : [Given that R = 8.31 J mol ^{–1} K^{-1} ]

Answer