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Thermodynamics

Question
CBSEENPH11026393

When an ideal monoatomic gas is heated at constant pressure, the fraction of the heat energy supplied which increases the internal energy of the gas is

  • 2 / 5

  • 3 / 5

  • 3 / 7

  • 5 / 7

Solution

B.

3 / 5

By first law of thermodynamics

    ΔQ = ΔU + ΔW

Where ΔQ = Heat supplied to the system by the surroundings

          ΔW = Work done by the system on the surroundings

          ΔU = change in internal energy of the system

         = f2 nRT + P dV

   Q = f2 nRT + PV

   Q = f2 nRT + nRT                (  PV = nRT )

      = 32 nRT + nRT

   Q = 52 nRT

Fraction of heat energy supplied increase the internal energy.

∴  Fraction of heat energy supplied

                   = UQ

                    =  32  nRT 52  nRT

                     = 35