b
\(\frac{{\text{1}}}{{\text{2}}}{A_{2(g)}} + \frac{3}{2}{B_{2(g)}} \to A{B_{3(g)}};\,\,\Delta H =  - 20\,kJ\)
 \(\Delta S = {S_{A{B_3}}} - \frac{1}{2}S{A_2} - \frac{3}{2}S{B_2}\)

\( = 50 - \frac{1}{2} \times 60 - \frac{3}{2} \times 40 \)

\(= 50 - 30 - 60 \)

\(= 50 - 90 =  - 40\,J{K^{ - 1}}\,mol{e^{ - 1}}\)

સંતુલને \({{\Delta G}} = {\text{0      - 20}} \times {\text{1}}{{\text{0}}^{\text{3}}} = T \times  - 40\)

\(T = \frac{{20 \times 1000}}{{40}} = 500\,\,\,Kelvin\)