What is the oxidation number of $Cl$ in $HClO_4$ and $HClO_3$?

The oxidation states of the two sulfur atoms in thiosulfuric acid $(H_2S_2O_3)$ are .....................

$A$ compound contains atoms $X$,$Y$,and $Z$. The oxidation number of $X$ is $+2$,$Y$ is $+5$ and $Z$ is $-2$. Therefore,a possible formula of the compound is

In which compound is the oxidation state of nitrogen $+1$?

What is the difference in the oxidation number of nitrogen when nitric acid is converted into nitrous oxide?

What are the oxidation numbers of the underlined elements in each of the following and how do you rationalise your results?
$(a)$ $K\underline {I_3}$
$(b)$ $H_2\underline {S_4}O_6$
$(c)$ $\underline {Fe_3}O_4$
$(d)$ $\underline {C}H_3\underline {C}H_2OH$
$(e)$ $\underline {C}H_3\underline {C}OOH$