Which of the following ions does not exist in an aqueous solution?

What is the basicity of orthophosphoric acid?

Reaction of zinc with cold and very dilute nitric acid yields

The bond energies (in $kJ \ mol^{-1}$) of $P-H$, $As-H$, and $N-H$ are respectively:

$HNO_3$ is produced in good yield by which of the following methods?

$p$-Block elements form acidic,basic,and amphoteric oxides. Explain each property by giving two examples and also write the reactions of these oxides with water.