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

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 = \dfrac{{q}_{rev}}{T}

(D)

\Delta H = \Delta U - \Delta nRT

Choose the most appropriate answer from the options given below :

Quantrex Academy · Accepted Answer

Correct answer: B. B and C only

The Gibbs free energy can be written as a function of enthalpy and entropy as follows,

(B) $G = H - TS$

At constant $T$

$\Delta G = \Delta H - T \Delta S$

(A) According to first law of thermodynamics, $\Delta U = Q + W$

If we apply constant $P$ and reversible work.

$W = - P ∆ V$

$\Delta U = Q - P \Delta V$

(C) By definition of entropy change $dS = \dfrac{{dq}_{rev}}{T}$

At constant $T$

$\Delta S = \dfrac{{q}_{rev}}{T}$

Enthalpy can be written as a function of internal energy, pressure and volume as follows,

(D) $H = U + PV$

For ideal gas equation, $PV = nRT$

$H = U + nRT$

At constant $T$

$\Delta H = \Delta U + \Delta nRT$

Which of the following relations are correct? (A) Δ U = q + p Δ V...