Acidified $KMnO_4$ is decolourised by:

Which of the following options are correct for the reaction
$2[Au(CN)_2]_{(aq)}^{-} + Zn_{(s)} \rightarrow 2Au_{(s)} + [Zn(CN)_4]_{(aq)}^{2-}$
$A.$ Redox reaction
$B.$ Displacement reaction
$C.$ Decomposition reaction
$D.$ Combination reaction
Choose the correct answer from the options given below:

Which one of the following reactions is not possible?

$Cu^{2+}(aq.)$ does not undergo a redox reaction with a solution of:

How many moles of $K_2Cr_2O_7$ are reduced by $1$ mole of $Sn^{2+}$?

Which of the following reagents forms a green precipitate $(ppt)$ with $KI$?