The oxidation state of $P$ in $KH_2PO_2$ is .........

What is the oxidation number of $N$ in $HNO_4$?

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

$KMnO_4$ acts as an oxidising agent in the neutral medium and gets reduced to $MnO_2$. What is the equivalent weight of $KMnO_4$ in a neutral medium?

$2.5 \ mol$ of hydrazine $(N_2H_4)$ loses $25 \ mol$ of electrons to form a new compound $X$. Assuming all lost electrons are contained in the new compound,what is the oxidation state of nitrogen in compound $X$?

Oxygen has an oxidation state of $+2$ in which of the following compounds?