Oxidation State Questions

Consider the following compounds: $\underline{\text{K}}{\text{O}}_2$, ${\text{H}}_2{\underline{\text{O}}}_2$ and ${\text{H}}_2\underline{\text{S}}{\text{O}}_4$. The oxidation states of the underlined elements in them are, respectively:

Which one of the elements with the following outer orbital configurations may exhibit the largest number of oxidation states?

Oxidation states of $\text{P}$ in ${\text{H}}_4{\text{P}}_2{\text{O}}_5,{\text{H}}_4{\text{P}}_2{\text{O}}_6,{\text{H}}_4{\text{P}}_2{\text{O}}_7$, are respectively:

In which of the following compounds, nitrogen exhibits highest oxidation state?

A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?