The gas produced from thermal decomposition of $(NH_4)_2Cr_2O_7$ is

Identify the correct set of $13^{th}$ group elements which do not form amphoteric oxides?

What is produced when $HNO_3$ reacts with $P_4O_{10}$?

Which two gases react to form dense white fumes?

The structure of orthophosphoric acid is

In the ring test of $NO_{3}^{-}$ ion,$Fe^{2+}$ ion reduces nitrate ion to nitric oxide,which combines with $Fe^{2+}_{(aq)}$ ion to form a brown complex. Write the reactions involved in the formation of the brown ring.