What is the oxidation state of $Mn$ in $MnO_4^{-}$?

What is the change in oxidation number of carbon in the following reaction?
$CH_{4(g)} + 4Cl_{2(g)} \rightarrow CCl_{4(l)} + 4HCl_{(g)}$

The oxidation states of the two sulfur atoms in thiosulfuric acid $(H_2S_2O_3)$ are .....................

Oxidation number of potassium in $K_2O$,$K_2O_2$ and $KO_2$,respectively,is

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

What is the change in the oxidation number of nitrogen when $NO_3^{-}$ is converted to $NH_4^{+}$ ion?