Chemical Equilibrium

$K_C$ for the reaction, $A_2(g) \stackrel{T(\mathrm{~K})}{\rightleftharpoons} B_2(g)$ is 99.0 . In a 1 L closed flask two moles of $B_2(g)$ is heated to $T(\mathrm{~K})$. What is the concentration of $B_2(g)\left(\right.$ in $\left.\mathrm{mol} \mathrm{L}^{-1}\right)$ at equilibrium?