Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Na_2CrO_4 + AgF \longrightarrow Ag_2CrO_4 \downarrow + NaF$

Potassium permanganate acts as an oxidant in neutral,alkaline,as well as acidic media. The final products obtained from it in the three conditions are,respectively:

The treatment of an aqueous solution of $3.74 \ g$ of $Cu(NO_3)_2$ with excess $KI$ results in a brown solution along with the formation of a precipitate. Passing $H_2S$ through this brown solution gives another precipitate $X$. The amount of $X$ (in $g$) is. . . . . [Given : Atomic mass of $H=1, N=14, O=16, S=32, K=39, Cu=63, I=127$ ]

When $KMnO_4$ solution is titrated with a solution containing $Fe^{2+}$ ions,the indicator used in this titration is

$KMnO_4$ acts as an oxidising agent in acidic medium. $X$ is the difference between the oxidation states of $Mn$ in reactant and product. $Y$ is the number of $d$ electrons present in the brown red precipitate formed at the end of the acetate ion test with neutral ferric chloride. The value of $X+Y$ is $.........$

Which of the following is not true for $(i)$ $Zn +$ dilute $HCl$ and $(ii)$ $Zn +$ concentrated $HCl$?