At what temperature is red phosphorus heated to obtain $\alpha$-black phosphorus (in $K$)?

$NO_2$ gas is

Which element among the following forms $P \pi-P \pi$ multiple bonds?

Why does $NO_2$ dimerise?

Describe the preparation,properties,and structures of oxides of nitrogen.

White phosphorus is heated with concentrated $NaOH$ in $CO_2$ atmosphere to form a gas $A$ and compound $B$. When $A$ is bubbled into aqueous $CuSO_4$ solution,copper phosphide and $C$ are formed. $B$ and $C$ are respectively: