The number of moles of $KMnO_4$ required to oxidize one equivalent of $KI$ in the presence of sulphuric acid is

In acidic medium,the required number of moles of ferrous oxalate $(FeC_2O_4)$ for the reduction of $2.5 \, mol$ of $KMnO_4$ is:

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

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$KNO_2 + AgF \longrightarrow AgNO_2 \downarrow + KF$

Upon the addition of a solution $A$ to a strongly acidified solution of barium nitrate,a white precipitate was obtained which did not dissolve even after large addition of water. Solution $A$ contained

Which of the following decolourises the colour of acidic $KMnO_4$?