CrO is basic but $\mathrm{Cr}_2 \mathrm{O}_3$ is amphoteric.

Nitrite is oxidised to nitrate in acidic medium by $\mathrm{KMnO}_4$.

$\mathrm{PdCl}_2$ is the catalyst in Wacker process.

The reactivity of the earlier members of lanthanide series is similar to that of aluminium.

$+2,+5$

$+3,+3$

$+5,+5$

$+5,+2$

5

4

3

6

A-V, B-III, C-IV, D-II

A-IV, B-V, C-I, D-III

A-I, B-III, C-IV, D-V

A-V, B-III, C-I, D-II