Balance the following redox reactions using the oxidation number and ion-electron method:
$(1) \ Zn + NO_3^- + H^+ \to Zn^{2+} + N_2O + H_2O$
$(2) \ I^- + O_2 + H_2O \to I_2 + OH^-$
$(3) \ MnO_4^- + C_2H_5OH \to Mn^{2+} + CH_3COOH$

Which of the following are redox changes?
$(i)$ Hydrolysis of $XeF_2$
$(ii)$ Thermal decomposition of $Ag_2CO_3$
$(iii)$ Reaction of $Al$ with $NaOH$
$(iv)$ Hydrolysis of $PCl_5$
$(v)$ Reaction of $NaCl$ with conc. $H_2SO_4$
Correct options are:

$A$ white crystalline salt $[A]$ reacts with dilute $HCl$ to produce a suffocating gas $[B]$ and also forms a yellow precipitate. When gas $[B]$ is passed through acidified potassium dichromate,it turns the solution green,forming $[C]$. Identify $A, B$,and $C$ respectively.

Consider the following reactions (unbalanced):
$Zn +$ hot conc. $H_2SO_4 \rightarrow G + R + X$
$Zn +$ conc. $NaOH \rightarrow T + Q$
$G + H_2S + NH_4OH \rightarrow Z$ (a precipitate) $+ X + Y$
Choose the correct option$(s)$.
$(1)$ The oxidation state of $Zn$ in $T$ is $+1$
$(2)$ Bond order of $Q$ is $1$ in its ground state
$(3)$ $Z$ is dirty white in colour
$(4)$ $R$ is a $V$-shaped molecule

For the reaction $4Fe + 3O_2 \to 4Fe^{3+} + 6O^{2-}$,which of the following statements is incorrect?

Assign $A, B, C, D$ from the given type of reaction.
$Ba(NO_3)_2 + Na_2SO_4 \longrightarrow BaSO_4 \downarrow + 2NaNO_3$