What is the oxidation number of $Cr$ in $K_{2}Cr_{2}O_{7}$?

Write the oxidation number of the carbon atom in the carboxyl group of acetic acid $(CH_3COOH)$.

What are the oxidation states of three $Br$ atoms in $Br_3O_8$ molecule?

$2$ mole of $N_2H_4$ loses $16$ mole of electrons and is converted to a new compound $X$. Assuming that all of the $N$ atoms appear in the new compound,what is the oxidation state of $N$ in $X$?

What is the oxidation number of $S$ in $SO_4^{2-}$?

$KMnO_4$ 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?