Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Pb(NO_3)_2 + H_2SO_4 \longrightarrow PbSO_4 \downarrow + 2HNO_3$

In chloro-alkali industries,during the Solvay ammonia process,a redox change occurs during:

In the reaction of phosphorus with concentrated $HNO_3$,the oxidized and reduced products respectively are

Given below are two statements :-
Statement $I$ :- In redox titration,the indicators used are sensitive to change in $pH$ of the solution.
Statement $II$ :- In acid-base titration,the indicators used are sensitive to change in oxidation potential.
In the light of the above statements,choose the most appropriate answer from the options given below.

When a manganous salt is fused with a mixture of $KNO_3$ and solid $NaOH$, the oxidation number of $Mn$ changes from $+2$ to:

$CO_2$ and $SO_2$ gases can be distinguished by using: