The oxidation number of carbon in $CH_2Cl_2$ is

The oxidation state of $Cr$ in $CrO_5$ is

In which substance does nitrogen exhibit the lowest oxidation state?

$A$ compound of $Xe$ and $F$ is found to have an atomic ratio $Xe : F$ as $0.4 : 2.4$. Find the oxidation number of $Xe$.

When $K_2Cr_2O_7$ is converted to $K_2CrO_4$,the change in the oxidation state of chromium is

The compound $YBa_2Cu_3O_7$,which shows superconductivity,has copper in an oxidation state of ........ Assume that the rare earth element Yttrium is in its usual $+3$ oxidation state.