# NEET Physics Thermodynamics Questions Solved

An ideal gas expands isothermally from a volume V1 to V2 and then compressed to original volume V1 adiabatically. Initial pressure is P1 and final pressure is P3. The total work done is W. Then -

(1) ${P}_{3}>{P}_{1},\text{\hspace{0.17em}\hspace{0.17em}}W>0$

(2) ${P}_{3}<{P}_{1},\text{\hspace{0.17em}\hspace{0.17em}}W<0$

(3) ${P}_{3}>{P}_{1},\text{\hspace{0.17em}\hspace{0.17em}}W<0$

(4) ${P}_{3}={P}_{1},\text{\hspace{0.17em}\hspace{0.17em}}W=0$

(3) From graph it is clear that P3 > P1.

Since area under adiabatic process (BCED) is greater than that of isothermal process (ABDE). Therefore net work done

$W={W}_{i}+\left(-{W}_{A}\right)$    $\left(\because \text{\hspace{0.17em}}{W}_{A}>{W}_{i}\right)$

W < 0

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