Suppose 0.086 mol of $\mathrm{Br}_{2}$ is placed in a $1.26-\mathrm{L}$. flask and heated to $1756 \mathrm{K},$ a temperature at which the halogen dissociates to atoms
$$
\operatorname{Br}_{2}(\mathrm{g}) \rightleftarrows 2 \operatorname{Br}(\mathrm{g})
$$
If $\mathrm{Br}_{2}$ is $3.7 \%$ dissociated at this temperature, calculate $K_{\mathrm{c}} .$