The oxidation number of $Cr$ in $K_3CrO_8$ is $+5$. How many peroxy linkages are present in this molecule?

$2.5 \ mol$ 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 $X$?

The oxidation state of chlorine in perchloric acid $(HClO_4)$ is:

Arrange $ICl$,$HI$,$I_2$,and $HIO_4$ in the decreasing order of the oxidation number of iodine.

One mole of $N_2H_4$ loses $10 \ mol$ of electrons to form a new compound $Y$. Assuming that all nitrogen atoms appear in the new compound,what is the oxidation state of $N$ in $Y$? (There is no change in the oxidation state of hydrogen)

The correct formula for the paramagnetic acid is: