Oxidation number of $As$ atoms in $H_3AsO_4$ is

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

The oxidation states of iodine in $HIO_4$,$H_3IO_5$,and $H_5IO_6$ are respectively:

What is the correct order of decreasing oxidation state of iodine in the following compounds?

What is the oxidation number of sulphur in $Na_2S_4O_6$?

In the following reaction,assign the state for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{Cl_2}O + H_2O \longrightarrow 2HClO$