Which statements about the thiosulphate ion are correct? One or more options may be correct.

AWith dilute HCl it gives a turbidity of sulphur and evolves $SO X_{2}$ .
BThe average oxidation state of sulphur in $S X_{2} O X_{3} X^{2 -}$ is $+ 2$ .
CIt reduces iodine to iodide, forming tetrathionate: $2 S X_{2} O X_{3} X^{2 -} + I X_{2} S X_{4} O X_{6} X^{2 -} + 2 I X^{-}$ .
DWith dilute HCl it gives a perfectly clear solution and no gas.

Answer: A, B, C

S X_{2} O X_{3} X^{2 -} + 2 H X^{+} S + SO X_{2} + H X_{2} O

gives both turbidity and

SO X_{2}

. The average S oxidation state is

2 x + 3 (- 2) = - 2

, so

x = + 2

. Iodine oxidises it to

S X_{4} O X_{6} X^{2 -}

(charge and atoms balance). The clear-solution statement is false. Correct: first three.