Question

One mole of an ideal mono-atomic gas is subjected to a cyclic process connecting the states $L,M$ and $N$ as shown in the pressure - temperature diagram given below. The line $LM$ passes through the origin, while $MN$ and $LN$ are parallel to the pressure and temperature axes respectively.
The correct statements is : ($R$ is the universal gas constant).

• A. Work done along the path $LM$ is $300R$
• B. Work done along the path $NL$ is $750R$
• C. Work done along the path $LM$ is zero
• D. Enthalpy change along the path $MN$ is greater than zero

Answer 1

Answer: (C)

Work done along the path $LM$ is zero

The $LM$ is a straight line which is uniformly increasing for $P-T$ curve. Therefore, $LM$ is a constant volume process.

$\therefore \Delta V=0⟶forLM$

$\therefore$ It is an isochoric process.

$\therefore$ Work done along the path $LM=-P\Delta V=0$