Question

Dinitrogen and dioxygen are main constituents of air but these do not react
with each other to form oxides of nitrogen because _________.

• A. the reaction can be initiated only in presence of a catalyst.
  
• B. the reaction is endothermic and requires very high temperature
• C. oxides of nitrogen are unstable.
  
• D. $N_2$ and $O_2$ are unreactive.

Answer 1

The correct option is B the reaction is endothermic and requires very high temperature

The two main constituent gases of air are dinitrogen and dioxygen. Although being present in large amounts in air, they do not react with each other to form oxides of nitrogen. This is because dinitrogen has a triple bond between the two nitrogen atoms and for dinitrogen and dioxygen to react, this triple bond needs to be broken.

Therefore, for this reaction to take place, it would require very high temperature to generate enough energy to break the triple bond in dinitrogen.

Hence, option (A) is correct.