The equilibrium constants for the reaction  $B{r}_2\rightleftharpoons 2Br$ at 500K and 700 K are  $1x{10}^{-10}$ and   $1x{10}^{-5}$respectively. The reaction is

Chemical equilibrium constant for the reaction is ${\mathrm{Br}}_2\rightleftharpoons 2\mathrm{Br}\text{ is }{\mathrm{K}}_{\mathrm{c}}=\frac{[\mathrm{Br}{]}^2}{\left[{\mathrm{Br}}_2\right]}$

The value of ${\mathrm{K}}_{\mathrm{c}}\text{ at }500\mathrm{K}\text{ is }1\times {10}^{-10}\text{. }$One increasin tem rature (700 K). The value of K_c is also increased, i.e., the concentration of the product is increased and obviously the increase in temperature will favour the forward reaction. Thus, the forward reaction is endothermic.