$X + H_2SO_4 \to Y$ (colorless gas) and $Y + K_2Cr_2O_7 + H_2SO_4 \to$ green solution. Then $X$ and $Y$ are respectively ........

What are $X$ and $Y$ in the following reactions?
$(i) \ MnO_4^{-} + I^{-} \xrightarrow{H^{+}} X$
$(ii) \ MnO_4^{-} + I^{-} \xrightarrow{H_2O} Y$

To an acidified dichromate solution,a pinch of $Na_2O_2$ is added and shaken. What is observed?

The colour of an iodine solution is discharged by shaking it with an aqueous solution of:

Aqueous sulphite reacts with dilute sulphuric acid to form $X_{(g)}$. The liberated $X_{(g)}$ is passed into acidified $KMnO_4$ solution. What is the oxidation state of $Mn$ in the product formed?

Assign $A, B, C, D$ from the given type of reaction:
$2FeCl_3 + 3KI \longrightarrow 2FeCl_2 + I_2 + 2KCl$
$I_2 + KI \longrightarrow KI_3$
Identify the observation for the product $KI_3$ in the reaction $FeCl_3 + KI \longrightarrow Fe^{2+}(aq.) + KI_3$.