When `SO_2` is passed through acidified solution of `H_2S`

When SO_(2) is passed through acidified solution of H_(2)S

When SO_2 is passed through acidified KMnO_4 solution

When SO_2 gas is passed through an acidified solution of K_2 Cr_2 O_7 , the solution turns ___ in colour.

When SO_2 gas is passed through an acidified solution of K_2 Cr_2 O_7 , the solution turns ___ in colour.