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Question: Answered & Verified by Expert
Based on first law of thermodynamics which of the following is correct
ChemistryThermodynamics (C)MHT CETMHT CET 2019 (Shift 1)
Options:
  • A For an isobaric process, qp=ΔU+w
  • B For an adiabatic process, ΔU=-w
  • C For an isochoric process, ΔU=-qv
  • D For an isothermal Process, q=+w
Solution:
2564 Upvotes Verified Answer
The correct answer is: For an isobaric process, qp=ΔU+w
In isobaric process, pressure is constant and volume increase from V1 to V2 due to the absorption of heat. According to the first law of thermodynamics, ΔU=q+W
At constant pressure, qp=ΔU-W
qp=ΔU-pΔV
qp=U2-U1--pV2-V1
qp=U2+pV2-U1+pV1
qp=H2-H1
qp=ΔH                                                ...(i)
As we know, ΔH=ΔU+pΔV
ΔH=ΔU+W
Putting the value of ΔH in (1)
qp=ΔU+W
Other corrected options are as follows:
For adiabatic process, ΔU=W
For an isochoric process, ΔU=qv
For an isothermal process q=-W

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