The redox reaction among the following is

$Fe^{3+}$ is reduced to $Fe^{2+}$ by using:
$A$. $H_2O_2$ in presence of $NaOH$
$B$. $Na_2O_2$ in water
$C$. $H_2O_2$ in presence of $H_2SO_4$
$D$. $Na_2O_2$ in presence of $H_2SO_4$

Assign $A, B, C, D$ for the given type of reaction:
$Mn(NO_3)_2 + 2NaOH \longrightarrow Mn(OH)_2 \downarrow + 2NaNO_3$

Which of the following reagents forms a green precipitate $(ppt)$ with $KI$?

Given below are two statements.
Statement-$I$: In the decomposition of potassium chlorate,$Cl$ is reduced.
Statement-$II$: Reaction of $Na$ with $O_2$ to form $Na_2O$ is a redox reaction.
The correct answer is

$1 \text{ mole of } H_2C_2O_4 \text{ is oxidised by } x \text{ mole of } MnO_4^- \text{ in strong basic medium and } 1 \text{ mole of } NaHC_2O_4 \text{ is oxidised by } y \text{ mole of } MnO_4^- \text{ in acidic medium. Ratio of } x/y \text{ is}$