Among the following variable valency is exhibited by                                         

Reason: Fe exhibits 3 & 2 valency’s in $\text{FeC}{l}_3\text{ \& FeC}{l}_2$  ‘Au’ exhibits 1 & 3 valencies in $\text{AuC}l\&\text{AuC}{l}_3$  and ‘S’ exhibits 2, 4, 6.

Sol:      $\text{Fe}\to {\text{Fe}}^{+2}{\text{Fe}}^{+3}$

            $\text{Au}\to {\text{Au}}^{+},{\text{Au}}^{+3}$

            $\text{S}\to {\text{S}}^{+2},{\text{S}}^{+4}{\text{S}}^{+6}$