The oxidation number of sulphur in $H_2SO_4$ is

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.

The compound $YBa_2Cu_3O_7$,which shows superconductivity,has copper in an oxidation state of ........ Assume that the rare earth element Yttrium is in its usual $+3$ oxidation state.

What are the oxidation states of $P$ in $H_4P_2O_5$,$H_4P_2O_6$,and $H_4P_2O_7$ respectively?

Which of the following statements is not correct?

Assign oxidation number to the underlined elements in each of the following species:
$(a)$ $NaH_2\underline{P}O_4$
$(b)$ $NaH\underline{S}O_4$
$(c)$ $H_4\underline{P_2}O_7$
$(d)$ $K_2\underline{Mn}O_4$
$(e)$ $Ca\underline{O_2}$
$(f)$ $Na\underline{B}H_4$
$(g)$ $H_2\underline{S_2}O_7$
$(h)$ $KAl(\underline{S}O_4)_2 \cdot 12H_2O$