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A mass of diatomic gas left parenthesis straight gamma space equals space 1.4 right parenthesis at a pressure of 2 atm is compressed adiabatically so that its temperature rise from 27oC to 927o C. The pressure of the gas is final state is 

  • 28 atm

  • 68.7 atm

  • 256 atm

  • 256 atm


C.

256 atm

T1 = 273 + 27 = 300k
T2 = 273+927 = 1200 K
Gas equation for adiabatic process

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During an isothermal expansion, a confined ideal gas does - 150 J of work against its surroundings. This implies that

  • 300 J of heat has been added to the gas

  • no heat is transferred because the process is isothermal

  • 150 J of heat has been added to the gas

  • 150 J of heat has been added to the gas


C.

150 J of heat has been added to the gas

From the first law of thermodynamics

ΔU = Q + W

For isothermal process, ΔU = 0

therefore, Q = - W

Given W = - 150 

Therefore, Q = + 150

When Q is positive, the heat is added to the gas.

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4.0 g of a gas occupies 22.4 L at NTP. The specific heat capacity of the gas at constant volume is 5.0 JK-1 mol-1. If the speed of sound in this gas at NTP is 952 ms-1, then the heat capacity at constant pressure is.
(Take gas constant R = 8.3 Jk-1 mol-1)

  • 8.0 JK-1mol-1

  • 7.5 JK-1mol-1

  • 7.0 JK-1mol-1

  • 7.0 JK-1mol-1


A.

8.0 JK-1mol-1

Given, M = 4 gm

V= 22.4 L, 

CV = 5 JK-1 mol-1

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When 1 kg of ice at 0oC  melts to water 0oC, the resulting change in its entropy, taking latent heat of ice to be 80 cal/oC, is

  • 8 x 104 cal /K

  • 80 cal/K

  • 293 cal/ K

  • 293 cal/ K


C.

293 cal/ K

Change in entropy


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An ideal gas is compressed to half its initial volume by means of several process. Which of the process results in the maximum work done on the gas?

  • Adiabatic

  • Isobaric

  • Isochoric 

  • Isochoric 


A.

Adiabatic

Given, ideal gas is compressed to half its initial volume i.e.,

Vo = V/2


The isochoric process is one in which volume is kept constant, meaning that work done by the system will be zero  ie.e Wisochoric  = 0

As we know, work done on the gas  = Area under curve  i.e,

Wadiabatic > Wisothrmal > Wisochoric

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