Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$2BaCrO_4 \downarrow + 4HCl \longrightarrow 2BaCl_2 + H_2Cr_2O_7 + H_2O$

Identify whether the following reactions act as oxidation or reduction processes:
$(i) \ S + 6HNO_3 \to H_2SO_4 + 6NO_2 + 2H_2O$
$(ii) \ 2K + Br_2 \to 2KBr$

In order to oxidize a mixture of $1 \text{ mole}$ each of $FeC_2O_4$, $Fe_2(C_2O_4)_3$, $FeSO_4$, and $Fe_2(SO_4)_3$ in an acidic medium, the number of moles of $KMnO_4$ required is:

$50 \ mL$ of $0.1 \ M$ solution of a salt reacted with $25 \ mL$ of $0.1 \ M$ solution of sodium sulphite. The half-reaction for the oxidation of sulphite ion is:
$SO_{3}^{2-} (aq) + H_{2}O (l) \to SO_{4}^{2-} (aq) + 2H^{+} (aq) + 2e^{-}$
If the oxidation number of the metal in the salt was $+3$,what would be the new oxidation number of the metal?

Which of the following reactions does not involve either oxidation or reduction?
$I. \ 2Cs + 2H_2O \to 2CsOH + H_2$
$II. \ 2CuI_2 \to 2CuI + I_2$
$III. \ NH_4Br + KOH \to KBr + NH_3 + H_2O$
$IV. \ 4KCN + Fe(CN)_2 \to K_4[Fe(CN)_6]$

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