Which of the following is the correct formula for nitrogen monoxide?

The formula for nitrogen monoxide is correctly identified as NO. This compound consists of one nitrogen atom bonded to one oxygen atom. The naming follows standard nomenclature rules where the prefix "mono-" is implied for the single nitrogen and oxygen present, hence the name "nitrogen monoxide."

Nitrogen monoxide is a simple molecule and serves as the basis for understanding more complex nitrogen oxides. The incorrect options represent different compounds. N2O is dinitrogen monoxide (also known as nitrous oxide), which has two nitrogen atoms and one oxygen atom. N2O5 contains two nitrogen atoms and five oxygen atoms, making it dinitrogen pentoxide. NO2, known as nitrogen dioxide, consists of one nitrogen and two oxygen atoms. Each of these compounds has distinct chemical properties and uses in various chemical reactions, further highlighting the importance of accurate nomenclature and formula representation in chemistry.