Acidified potassium permanganate solution is decolourised by

Acidified potassium permanganate solution is decolourised by

Acidified $KMnO_4$ can be decolourised by

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

Which of the following will not change the orange colour of $K_2Cr_2O_7$ into green colour in an acidic medium?

The sodium salt of an organic acid $'X'$ produces effervescence with conc. $H_2SO_4$. $'X'$ reacts with an acidified aqueous $CaCl_2$ solution to give a white precipitate which decolourises an acidic solution of $KMnO_4$. $'X'$ is: