The product $D$ in the following reaction sequence is:

What volume of $O_{2(g)}$ measured at $1 \ atm$ and $273 \ K$ will be formed by the action of $100 \ mL$ of $0.5 \ N \ KMnO_4$ on hydrogen peroxide in an acidic solution? The skeleton equation for the reaction is: $KMnO_4 + H_2SO_4 + H_2O_2 \to K_2SO_4 + MnSO_4 + O_2 + H_2O$.

$SO_2$ can reduce:

Iodine is released when potassium iodide reacts with

Assign $A, B, C, D$ from the given type of reaction.
$KMnO_4 + NaNO_3 \longrightarrow$ No reaction

When copper is added to concentrated $H_2SO_4$,$CuSO_4$ is produced along with another sulphur-containing compound $X$. The compound $X$ is