Question

Which among the following relations is/are valid only for reversible process undergone by a pure substance?

• A. $TdS=dU+\delta W$
• B. $\delta Q=PdV+dU$
• C. $TdS=dU+PdV$
• D. $\delta Q=dU+\delta W$

Answer 1

The correct option is B $\delta Q=PdV+dU$

As we know according to l-law of thermodynamics,
$\delta Q=dU+\delta W$
Conditions for applying the equation,
$\delta W=\int PdV$ are:
(i) the sysem must be a closed system.
(ii) Work should cross the boundary.
(iii) the process must be a reversible process.
So, $\delta Q=dU+PdV$