Q 51 :

When 300 J of heat is given to an ideal gas with Cp=72R its temperature raises from 20°C to 50°C keeping its volume constant. The mass of the gas is (approximately) _______ g.    (R=8.314  J/mol.K)                   [2026]



(481)

 



Q 52 :

One mole of an ideal diatomic gas expands from volume V to 2V isothermally at a temperature 27 °C and does W joule of work. If the gas undergoes same magnitude of expansion adiabatically from 27 °C doing the same amount of work W, then its final temperature will be (close to) ______ °C.

(log2 = 0.693)   [2026]

  • −189

     

  • −117

     

  • −30

     

  • −56

     

(4)

 



Q 53 :

The internal energy of a monoatomic gas is 3nRT. One mole of helium is kept in a cylinder having internal cross sectional area of 17 cm² and fitted with a light movable frictionless piston. The gas is heated slowly by supplying 126 J heat. If the temperature rises by 4 °C, then the piston will move ____ cm.
(atmospheric pressure = 10 Pa)   [2026]

  • 15.5

     

  • 1.45

     

  • 14.5

     

  • 1.55

     

(1)

 



Q 54 :

A diatomic gas (γ=1.4) does 100 J of work when it is expanded isobarically. Then the heat given to the gas ______ J.      [2026]



(350)

w=100 J=nRΔT  for isobaric process.

Q=nCpΔT=(f2+1)nRΔT

=72·(100)=350 Joule.



Q 55 :

An insulated cylinder of volume 60 cm3 is filled with a gas at 27°C and 2 atmospheric pressure. Then the gas is compressed making the final volume as 20 cm3 while allowing the temperature to rise to 77°C. The final pressure is __________ atmospheric pressure.      [2026]



(7)

PV=nRT

P1V1RT1=P2V2RT2

2×105×60300=P2×20350

P2=2×105×7×36

P2=7×105=7 atm
 



Q 56 :

In the following p-V diagram, the equation of state along the curved path is given by (V-2)2=4ap, where a is a constant. The total work done in the closed path is   [2026]

  • -1a

     

  • +13a

     

  • 12a

     

  • -13a

     

(4)