$A$ solution of a salt in dilute $H_2SO_4$ gives a blue color with starch iodide solution. This indicates the presence of which ion?

To a solution of a colourless efflorescent sodium salt, when dilute acid is added, a colourless gas is evolved along with the formation of a white precipitate. Acidified dichromate solution turns green when the colourless gas is passed through it. The sodium salt is

Which anion's aqueous solution gives a white precipitate with $AgNO_3$,which is soluble in excess $NH_4OH$?

$A$ white crystalline salt $A$ reacts with dilute $HCl$ to liberate a suffocating gas $B$ and also forms a yellow precipitate. The gas $B$ turns potassium dichromate acidified with dilute $H_{2}SO_{4}$ to a green coloured solution $C$. $A$,$B$ and $C$ are respectively

Sodium sulphite on heating with dilute $HCl$ liberates a gas which

When $BaCl_{2}$ is added to an aqueous salt solution, a white precipitate is obtained. The anion among $CO_{3}^{2-}$, $SO_{3}^{2-}$, and $SO_{4}^{2-}$ that was present in the solution can be