Oxidation state of S in SO32− x+(−2×3)=−2 x=+6−2=+4
Oxidation state of S in S2O42− 2x4−(−2×4)=−2 2x=+8−2=+6 x=2+6=+3
Oxidation state of S in S2O62− 2x4−(−2x×6)=−2 2x=4−12−2=10 x=210=−5
Hence, increasing order of oxidation states of S is S2O42−<SO32−<S2O62−