Assign $A, B, C, D$ from the given type of reaction.
$Ba(OH)_2 + CO_2 \longrightarrow BaCO_3 \downarrow + H_2O$

By passing $H_2S$ gas in acidified $KMnO_4$ solution,we get

Assign $A, B, C, D$ from the given type of reaction.
$CaSO_4 + Pb(NO_3)_2 \longrightarrow PbSO_4 \downarrow + Ca(NO_3)_2$

$A$ 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.

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

$Zn_{(s)} + CuSO_{4(aq)} \rightarrow ZnSO_{4(aq)} + Cu_{(s)}$ is an example of which type of process?