$A_2O_x$ is oxidized to $AO_3^-$ by $MnO_4^-$ in acidic medium. If $1.5 \times 10^{-3} \text{ mole}$ of $A_2O_x$ requires $40 \text{ mL}$ of $0.03 \text{ M } KMnO_4$ solution in acidic medium,which of the following statement$(s)$ is/are correct?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Na_2S_2O_3 + BaCl_2 \longrightarrow BaS_2O_3 \downarrow + 2NaCl$

Suggest a scheme of classification of the following redox reactions:
$(a) N_{2(g)} + O_{2(g)} \rightarrow 2NO_{(g)}$
$(b) 2Pb(NO_3)_{2(s)} \rightarrow 2PbO_{(s)} + 4NO_{2(g)} + O_{2(g)}$
$(c) NaH_{(s)} + H_2O_{(l)} \rightarrow NaOH_{(aq)} + H_{2(g)}$
$(d) 2NO_{2(g)} + 2OH^{-}_{(aq)} \rightarrow NO_2^-(aq) + NO_3^-(aq) + H_2O_{(l)}$

Assign $A, B, C, D$ from given type of reaction.
$2KI + CuSO_4 \longrightarrow CuI \downarrow + \frac{1}{2}I_2 + K_2SO_4$

Which of the following are non-metal displacement reactions?
$(A)$ $Ca_{(s)} + 2 H_2 O_{(l)} \longrightarrow Ca(OH)_{2(aq)} + H_{2(g)}$
$(B)$ $V_2 O_{5(s)} + 5 Ca_{(s)} \stackrel{\Delta}{\longrightarrow} 2 V_{(s)} + 5 CaO_{(s)}$
$(C)$ $2 Fe_{(s)} + 3 H_2 O_{(g)} \stackrel{\Delta}{\longrightarrow} Fe_2 O_{3(s)} + 3 H_{2(g)}$
$(D)$ $Cr_2 O_{3(s)} + 2 Al_{(s)} \stackrel{\Delta}{\longrightarrow} Al_2 O_{3(s)} + 2 Cr_{(s)}$

Consider the following redox reaction in basic medium.
$x \ Cr(OH)_3 + y(IO_3)^{-} + z(OH)^{-} \rightarrow a(CrO_4)^{2-} + b(I)^{-} + c(H_2O)$
The incorrect option about it is