The oxidation number of $P$ in $Mg_3(PO_4)_2$ is ........

Consider the following molecules: $Br_3O_8$,$F_2O$,$H_2S_4O_6$,$H_2S_5O_6$,and $C_3O_2$. Count the number of atoms existing in their zero oxidation state in each molecule. Their sum is . . . . .

$A, B,$ and $C$ are three elements forming a compound in which their oxidation states are $+2, +5,$ and $-2$ respectively. If the compound is neutral,which of the following represents the formula of the compound?

What is the oxidation number of carbon in $K_2C_2O_4$?

The oxidation numbers of sulphur in $S_8$,$S_2F_2$,and $H_2S$ respectively,are:

Given below are two statements.
Statement $I$ : In $H_2O_2$, each oxygen atom is assigned an oxidation number of $-1$, and in $RbO_2$, each oxygen atom is assigned an oxidation number of $-\frac{1}{2}$.
Statement $II$ : The representation of $HAuCl_4$ and $MnO_2$ in Stock notation is $HAu(III)Cl_4$ and $Mn(IV)O_2$ respectively.
Examine the above statements and choose the correct answer.