$MnO_4^-$ on reduction in acidic medium forms

Which of the following reactions is a redox reaction?

The set of coefficients of $P_4$,$OH^{\Theta}$ and $H_2PO_2^{\Theta}$ in the balanced reaction $P_4 + OH^{\Theta} \to PH_3 + H_2PO_2^{\Theta}$ is

What is the number of moles of electrons gained by one mole of oxidizing agent in the following redox reaction?
$Zn_{(s)} + 2HCl_{(aq)} \longrightarrow ZnCl_2(aq) + H_2(g)$

$Mg$ (Magnesium) burns in $CO$ to produce

For the following balanced equation,$x, y$ and $z$ will be respectively:
$xMnO_4^- + yH^+ + ze^- \to 2Mn^{2+} + 4H_2O$