Sum of oxidation number of sulphur in ${\mathrm{S}}_8, {\mathrm{S}}_2{\mathrm{F}}_2, \mathrm{and} {\mathrm{H}}_2\mathrm{S}$ is:
 

Oxidation state of S in S8 is zero. Oxidation state of S in S₂F₂ is:

$$\begin{gathered} 2\left(\mathrm{oxidation} \mathrm{state} \mathrm{of} \mathrm{S}\right)+2(-1)=0 \\ \mathrm{oxidation} \mathrm{state} \mathrm{of} \mathrm{S}=+1 \end{gathered}$$

Oxidation state of S in H₂S:

$$\begin{gathered} \mathrm{Oxidation} \mathrm{state} \mathrm{of} \mathrm{S}+2\left(1\right)=0 \\ \mathrm{Oxidation} \mathrm{state} \mathrm{of} \mathrm{S}=-2 \end{gathered}$$

Sum of oxidation state of S₈, S₂F₂ and H₂S:

$1+0-2=-1$