Question

In the given figure, the initial and final states of a gas are shown by points $i$ and $f$. The internal energy of the gas at $i$ is $10\text{J}$.
For the path $iaf$ : $\Delta Q=50\text{J}$ and $\Delta W=20\text{J}$.
For the path $ibf$, if $\Delta Q=36\text{J},$ the value of $\Delta W$ will be equal to

• A. $4\text{J}$
• B. $12\text{J}$
• C. $18\text{J}$
• D. $6\text{J}$

Answer 1

The correct option is D $6\text{J}$

Initial and final states are same for process $iaf$ and $ibf$. So
$(\Delta U{)}_{iaf}=(\Delta U{)}_{ibf}$
$(\Delta Q-\Delta W{)}_{iaf}=(\Delta Q-\Delta W{)}_{ibf}$
$50-20=36-d{W}_{ibf}$
$\Rightarrow \Delta W_{ibf}=6\text{J}$
Hence, option $\left(d\right)$ is the correct answer.