c
\(\mathop {\,\,}\limits_{\mathop {at\,t = 0}\limits_{at\,eq.} } \mathop {\,\mathop {\mathop {2A{B_3}(g)}\limits_8 }\limits_{(8 - 2 \times 2)} }\limits_{ = 4}  \leftrightarrow \mathop {\mathop {\mathop {{A_2}(g)}\limits_0 }\limits_2 }\limits_2  + \mathop {\mathop {\mathop {3{B_2}(g)}\limits_0 }\limits_{3 \times 2} }\limits_6 \)

now \({K_C} = \frac{{[{A_2}]{{[{B_2}]}^3}}}{{{{[A{B_3}]}^2}}} = \frac{{2/1 \times {{[6/1]}^3}}}{{{{[4/1]}^2}}} = 27\)