For the reaction, $2{\mathrm{Cl}}_{\left(\mathrm{g}\right)}\to {\mathrm{Cl}}_{2\left(\mathrm{g}\right)}$, the correct option is 

 In the reaction,  $2{\mathrm{Cl}}_{\left(\mathrm{g}\right)}\to {\mathrm{Cl}}_{2\left(\mathrm{g}\right)}$, the randomness decreases as 2 moles of Cl(g) are converted to 1 mole of ${\mathrm{Cl}}_{2\left(\mathrm{g}\right)}$, thus, ${\mathrm{\Delta }}_{\mathrm{r}}\mathrm{S}<0$
Bond formation is always exothermic process, thus ${\mathrm{\Delta }}_{\mathrm{r}}\mathrm{H}<0$