Question

Which of the following values are incorrect for the cyclic process?

• A. $dU=0$
• B. $q=-W$
• C. $dH=0$
• D. $W=31.4J$

Answer 1

The correct option is D $W=31.4J$

Since it is a cyclic process, and internal energy is a state function, hence $dU=0$, for the same reason, `dH=0`.

Also from the first law of thermodynamics,
$q=\Delta U+(-W)\Rightarrow q=-W$

Also, $W$ = area covered by sphere = $\pi r^2$
$=\pi {\left[\frac{(V_2-V_1)}{2}\right]}^2=\frac{\pi \times (20{)}^2}{2^2}=100\pi =100\times 3.14=314J$