Manganese achieves its maximum oxidation state in which of these compounds:
${\mathrm{KMnO}}_4, {\mathrm{K}}_2{\mathrm{MnO}}_4, {\mathrm{MnO}}_2, {\mathrm{Mn}}_3{\mathrm{O}}_4$

Find the oxidation number of phosphorous in the following compounds.

Phosphorus acid $\left({\mathrm{H}}_3{\mathrm{PO}}_3\right)$

Find the oxidation number of phosphorous in the following compounds.

Orthophosphoric acid $\left({\mathrm{H}}_3{\mathrm{PO}}_4\right)$

Find the oxidation number of phosphorous in the following compounds.

Metaphosphoric acid $\left({\mathrm{HPO}}_3\right)$

Find the oxidation number of phosphorous in the following compounds.

Pyrophosphoric acid  $\left({\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7\right)$

Predict whether the given statements are true or false:

The oxidation number of oxygen is $+1$ in peroxides.

Predict whether the given statements are true or false: 

Oxidation number of oxygen is $+2$ in Oxygen difluoride.

Predict whether the given statements are true or false: 

Oxidation number of oxygen is $-\frac{1}{2}$ in superoxides.