Oxidation state of sulphur atoms in H2S4O6 are
+5 , 0 , 0 , +5
+6 , 0 , 0 , +6
+5 , -1 , -1 , +5
+2.5 , +2.5 , +2.5 , +2.5
H2S4O6 is called Tetrathionic acid