Oxidation number of nitrogen in $NaNO_2$ is

What is the change in oxidation number of nitrogen in the following conversion? $NO_3^{-} \longrightarrow NO_2$

When $KMnO_4$ is reduced with oxalic acid in acidic solution,the oxidation number of $Mn$ changes from

In the chemical reaction $Cl_2 + H_2S \to 2HCl + S$,the oxidation number of sulphur changes from

Match List $I$ with List $II$ and select the correct answer using the codes given below the lists:

List $I$ (Compound)	List $II$ (Oxidation state of $N$)
$(A)$ $NO_2$	$(1)$ $+5$
$(B)$ $HNO$	$(2)$ $-3$
$(C)$ $NH_3$	$(3)$ $+4$
$(D)$ $N_2O_5$	$(4)$ $+1$

Codes: $A \quad B \quad C \quad D$

What are the oxidation states of phosphorus in the following:
$(i)$ $H_{3}PO_{3}$
$(ii)$ $PCl_{3}$
$(iii)$ $Ca_{3}P_{2}$
$(iv)$ $Na_{3}PO_{4}$
$(v)$ $POF_{3}$