Oxidation Number

The oxidation state of Cr in  ${[\text{Cr}{({\text{NH}}_{\text{3}})}_{\text{4}}{\text{Cl}}_{\text{2}}]}^{+}$  is

The oxidation number of elements decreases across the period.

Discuss the trends of oxidation number across the period in the periodic table.

Give an example of limitation of oxidation number concept.

Write the limitation of oxidation number concept.

${\mathrm{CrO}}_5$ has a structure as shown below:

The oxidation number of chromium in the above compound is 

Which of the following oxidation states is/are shown by hydrogen?

The oxidation state of chromium in the final product formed by the reaction between $\mathrm{KI}$ and acidified potassium dichromate solution is

$1$ mole of ${\mathrm{FeSO}}_4$ (atomic weight is $55.84 \mathrm{g} {\mathrm{mol}}^{-1}$) is oxidized to ${\mathrm{Fe}}_2{\left({\mathrm{SO}}_4\right)}_3$. Calculate the equivalent weight of ferrous ion

One mole of hydrazine $\left(N_2{H}_4\right)$ loses 10 moles of electrons in a reaction to form a new compound $X.$ Assuming that all the nitrogen atoms in hydrazine appear in the new compound, what is the oxidation state of nitrogen in $X$ ? (Note There is no change in the oxidation state of hydrogen in the reaction)

Which of the following oxidation states is/are shown by hydrogen?

What is the oxidation state of $\mathrm{I}$ in ${\mathrm{INO}}_3$?

What is the oxidation number of copper in brass?

The oxidation state of nitrogen in dinitrogen trioxide is:

The heating of ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ produces another chromium compound along with ${\mathrm{N}}_2$ gas. The change of the oxidation state of $\mathrm{Cr}$ in the reaction is

The formal oxidation numbers of $\text{C}\text{r}$ and $\text{C}\text{l}$ in the ions ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$ and $\text{C}\text{l}{\text{O}}_3^{-}$, respectively are

How many of the following species have formal oxidation state of $\mathrm{N}$ or $\mathrm{P}$ as $\text{'}+5\text{'}$

${\mathrm{N}}_2{\mathrm{O}}_5, {\mathrm{NO}}_3^{-}, {\mathrm{NO}}_2^{-}, {\left[{\mathrm{PO}}_4\right]}^{3-}, {\mathrm{P}}_4{\mathrm{O}}_6, {\mathrm{P}}_4{\mathrm{O}}_{10}, {\mathrm{H}}_3{\mathrm{PO}}_3$

The species with an atom in $+6$ oxidation state is

Sulphur and rest of the elements of group 16 are less electronegative than oxygen. Therefore, their atoms cannot take up electrons easily. They can acquire ns²np⁶ configuration by sharing two electrons with the atoms of other elements and thus, exhibit +2 oxidation state in their compounds. In addition to this, their atoms have vacant d-orbitals in their valence shell to which electrons can be promoted from the p and s-orbitals of the same shell. As a result, they can show +4 and +6 oxidation states.

Like sulphur, oxygen does not show +4 and +6 oxidation states. The reason is :