MCQ
An ideal gas undergoes cyclic process as shown in density pressure graph. During the process $AB$ the work done $|W_{AB}| = 70\,J$ . During the process $BC$, the gas absorbs $150\,J$ of heat. During the process $CA$ , gas undergoes expansion and does $210\,J$ of work
  • A
    The efficiency of cyclic process is $33\%$
  • The efficiency of cyclic process is $66\%$
  • C
    The process $CA$ is adiabatic
  • D
    The process $BC$ is isothermal

Answer

Correct option: B.
The efficiency of cyclic process is $66\%$
b
  $Q$ $\Delta U$ $W$
$AB$ $-70$ $0$ $-70$
$BC$ $150$ $150$ $0$
$CA$ $60$ $-150$ $210$

$\eta=\frac{140}{210} \times 100 \%=60 \%$

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