For the reaction
2A(g) + B(s) ⇋ C(g) + D(g)
at 700 °C Kc = 63.4
0.680 moles of A and 0.680 moles of B are placed in a 1.00-L closed
container, heated to 700 °C and allowed to reach equilibrium. What
is the concentration of C once equilibrium is established?