H2S\mathrm{H}_{2} \mathrm{S}H2S
SO2\mathrm{SO}_{2}SO2
Na2 S2O3\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}Na2 S2O3
Na2 S\mathrm{Na}_{2} \mathrm{~S}Na2 S