Laughing gas is prepared by heating

How can you synthesise nitric oxide in the laboratory?

On heating,lead$(II)$ nitrate gives a brown gas $(A).$ The gas $(A)$ on cooling changes to a colourless solid/liquid $(B).$ $(B)$ on heating with $NO$ changes to a blue solid $(C).$ The oxidation number of nitrogen in solid $(C)$ is :

Write a note on allotropes of phosphorus.

In the following reaction,assign the correct option for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{N}_2O_3 + H_2O \longrightarrow 2HNO_2$

Which of the following substances is not an isomorphous true alum and is known as a pseudo alum?