Iodine is released when potassium iodide reacts with

In the reaction of gold with aqua regia,the oxidation state of Nitrogen changes from

Which of the following is $NOT$ a redox reaction?

How many moles of acidic $KMnO_4$ are required to oxidize $1$ mole of ferrous oxalate $(FeC_2O_4)$?

Why do the following reactions proceed differently? $Pb_{3}O_{4} + 8HCl \rightarrow 3PbCl_{2} + Cl_{2} + 4H_{2}O$ and $Pb_{3}O_{4} + 4HNO_{3} \rightarrow 2Pb(NO_{3})_{2} + PbO_{2} + 2H_{2}O$

Which of the following ions decolorizes acidic $KMnO_4$ solution?