Question

Which of the following relations are correct?
(A) $\Delta U=q+p\Delta V$
(B) $\Delta G=\Delta H-T\Delta S$
(C) $\Delta S=\frac{q_{\text{ rev }}}{T}$
(D) $\Delta H=\Delta U-\Delta nRT$
Choose the most appropriate answer from the options given below :

• A. C and D only
• B. B and C only
• C. A and B only
• D. B and D only

Answer 1

Answer: (B)

Only (B) and (C) are correct.
(B) $G=H-TS$
At constant $T$
$\Delta G=\Delta H-T\Delta S$
(A) First law is given by
$\Delta U=Q+W$
If we apply constant $P$ and reversible work.
$\Delta U=Q-P\Delta V$
(C)By definition of entropy changc
$dS=\frac{d{q}_{\text{ rev }}}{T}$
At constant $T$
$\Delta S=\frac{q_{\text{ rev }}}{T}$
(D) $H=U+PV$
For ideal gas
$H=U+nRT$
At constant $T$
$\Delta H=\Delta U+\Delta nRT$