Which of the following occurs with $KMnO_4$ in neutral or faintly alkaline medium?

Blue colouration is not produced when :

The reaction of $Na_2S_2O_3$ with iodine gives

Identify the redox reaction out of the following reactions and identify the oxidising and reducing agents in them.
$(d)$ $PCl_{3(l)} + 3H_2O_{(l)} \to 3HCl_{(aq)} + H_3PO_{3(aq)}$
$(e)$ $4NH_{3(aq)} + 3O_{2(g)} \to 2N_{2(g)} + 6H_2O_{(g)}$

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

$KMnO_4$ oxidises $S_2O_3^{2-}$ to $SO_4^{2-}$ in medium $x$ and $NO_2^-$ to $NO_3^-$ in medium $y$. $x$ and $y$ are respectively: