The oxidation number of iodine varies from:

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

The oxidation state of iodine in $I_3^{-}$ is:

What is the oxidation state of phosphorus in the phosphate ion $(PO_4^{3-})$?

The sum of oxidation states of all atoms in $Cr_{2}O_{7}^{2-}$ ion is

State whether the following statements are True or False:
$(1)$ The oxidation number of nitrogen in ammonium chloride $(NH_4Cl)$ is $(-3)$.
$(2)$ The oxidation number of $C$ in methyl chloride $(CH_3Cl)$ is $(-2)$.
$(3)$ In the following reaction,the oxidation number of $Br$ changes from $0$ to $+5$: $Br_2 \to BrO_3^-$.