Consider the following data for the reaction $\mathrm{X}_{2}(\mathrm{~g})+\mathrm{Y}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{XY}(\mathrm{g})$ at $600 \mathrm{~K}$. The $\Delta_{\mathrm{r}} \mathrm{G}^{\ominus}$ (in $\mathrm{kJ} \mathrm{mol}^{-1}$) for the reaction is: | Compound | $\Delta_{f} \mathrm{H}_{600 \mathrm{~K}}^{\ominus}$ ($\mathrm{kJ} \mathrm{mol}^{-1}$) | $\mathrm{S}_{600 \mathrm{~K}}^{\ominus}$ ($\mathrm{J} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$) | |----------|------------|------------| | $\mathrm{XY}(\mathrm{g})$ | 42 | 200 | | $\mathrm{X}_{2}(\mathrm{~g})$ | 8 | 140 | | $\mathrm{Y}_{2}(\mathrm{~g})$ | 80 | 250 |

JEE Main · 2026 · 05 Apr 2026 · Shift 2 · Chemical Thermodynamics

Consider the following data for the reaction

X_{2} (g) + Y_{2} (g) ⇌ 2 XY (g)

600 K

. The

Δ_{r} G^{⊖}

(in

kJ mol^{- 1}

) for the reaction is:

Answer: (B)

The standard reaction enthalpy is

Δ_{r} H^{⊖} = 2 (42) - 8 - 80 = - 4 kJ mo l^{- 1}

. The standard reaction entropy is

Δ_{r} S^{⊖} = 2 (200) - 140 - 250 = + 10 J mo l^{- 1} K^{- 1} = 0.010 kJ mo l^{- 1} K^{- 1}

. At

600 K

Δ_{r} G^{⊖} = Δ_{r} H^{⊖} - T Δ_{r} S^{⊖} = - 4 - 600 (0.010) = - 10 kJ mo l^{- 1}

JEE Main · 2026 · 05 Apr 2026 · Shift 2 · Single correct option