Given the reaction between two gases represented by A_2 and B_2 to...

Given the reaction between two gases represented by $A_2$ and $B_2$ to give the compound $A B(g)$. A_2(g)+B_2(g) $\rightleftharpoons$2 A B(g) At equilibrium, the concentration of $A_2=3.0 \times 10^{-3} \mathrm{M}$ of $B_2=4.2 \times 10^{-3} \mathrm{M}$ of $A B=2.8 \times 10^{-3} \mathrm{M}$ If the reaction takes place in a sealed vessel at $527^{{}^{\circ}} \mathrm{C}$, then the value of $K_c$ will be