91.

A mass of diatomic gas  at a pressure of 2 atm is compressed adiabatically so that its temperature rise from 27^oC to 927^o C. The pressure of the gas is final state is 

• 28 atm

• 68.7 atm

• 256 atm

• 256 atm

If ΔU and ΔW represent the increase in internal energy and work done by the system respectively in the thermodynamical process, which of the following is true?

• ΔU = - ΔW, in a adiabatic process

• ΔU = ΔW, in an isothermal process

• ΔU = ΔW, in an adiabatic process

• ΔU = ΔW, in an adiabatic process

A monatomic gas at pressure p₁ and V₁ is compressed adiabatically to 1/8 th its original volume. What is the final pressure of the gas?

• 64 p₁

• p₁

• 16 p₁

• 16 p₁

The internal energy change in a system that has absorbed 2 Kcal of heat and done 500 J of work is 

• 8900 J

• 6400 J

• 5400 J

• 5400 J

In a thermodynamic process which of the following statements is not true?

• In an adiabatic process, the system is insulated from the surroundings

• In an isochoric process pressure remains constant

• In an isothermal process, the temperature remains constant

• In an isothermal process, the temperature remains constant

If Q, E andW denote respectively the heat added, change in internal energy and the work done in a closed cycle process, then

• W =0

• Q = W = 0

• E=0

• E=0

In producing chlorine through electrolysis 100 W power at 125 V is being consumed. How much chlorine per min is liberated? ECE of chlorine is 0.367 x 10-6 kg/C

• 17.6 mg

• 21.3 mg

• 24.3 mg

• 24.3 mg

A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of source be increased so as to increase its efficiency by 50% of original efficiency?

• 275 K

• 175 K

• 250 K

• 250 K

The molar specific heat at constant pressure of an ideal gas is (7/2)R. The ratio of specific heat at constant pressure to that at constant volume is

• 7/5

• 8/7

• 5/7

• 5/7

Two rods A and B of different materials are welded together as shown in the figure. Their thermal conductivities are K₁ and K₂. The thermal conductivity of the composite rod will be

• 
• 

• k₁ + k₂

• k₁ + k₂