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A system is taken from state a to state c by two paths adc and abc as shown in the figure. The internal energy at a is Ua = 10 J. Along the path adc the amount of heat absorbed δQ1 = 50 J and the work done δW1 = 20 J whereas along the path abc the heat absorbed δQ2 = 36 J. The amount of work done along the path abc is
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- 6 J
- 10 J
- 12 J
- 36 J
Correct Option: A
From first law of thermodynamics
Qadc = ∆Uadc + Wadc
50 J = ∆Uadc + 20 J
∆Uadc = 30 J
Again , Qabc = ∆Uabc + Wabc
Wabc = Qabc – ∆Uabc
= Qabc – ∆Uadc
= 36 J – 30 J = 6 J
