What is the oxidation number of S\text{S}S in Na2S2O4⋅2H2O\text{Na}_2\text{S}_2\text{O}_4 \cdot 2\text{H}_2\text{O}Na2S2O4⋅2H2O?
+2+2+2
+4+4+4
+3+3+3
+6+6+6