What happens when `SO_2` is passed through an aqueous solution of Fe (III) salts?

Explanation

`SO_2` acts as a reducing agent and hence reduces an aqueous solution of Fe (III) to Fe (II).
`underset("Ferric ion")(2Fe^(3+)) +SO_2 +2H_2O rarr underset("Ferrous ion")(2Fe^(2+)) + SO_4^(2-) + 4H^(+)`