Which of the following substances are soluble in concentrated $HNO_3$?

Among the given oxides of nitrogen; $N_2O$,$N_2O_3$,$N_2O_4$ and $N_2O_5$,the number of compound/$(s)$ having $N-N$ bond is ...

In Haber's process,hydrogen is obtained by reacting methane with steam in the presence of $NiO$ as a catalyst. This process is known as steam reforming. Why is it necessary to remove $CO$ when ammonia is obtained by Haber's process?

Why is $N_2$ chemically inert?

Which of the following oxides of nitrogen is the anhydride of $HNO_3$?

Nitrogen exists as a diatomic molecule $(N_2)$ and phosphorus as $P_4$. Why?