Question

Nitric oxide becomes brown when released in the air. Explain.

Answer 1

An oxide is a chemical compound which contains at least one oxygen atom with any other element. Oxide is di anion of oxygen represented as ${{O}^{2-}}$ in this state the oxygen is present in -2 oxidation state and acts as an anion which carries negative charge.

Complete answer:
$NO$ is known by the name nitric oxide or nitrogen monoxide it is one of the principal oxides of nitrogen. Nitric oxide is a free radical which represents that it has no unpaired electrons. It can also be known as a heteronuclear diatomic molecule. Nitric oxide is used as an important intermediate in many organic reactions. Nitric oxide exists as a colourless gas.
Nitric oxide becomes brown when released in air as when it comes in contact with air then due to its reactive nature it reacts with oxygen and form nitrogen dioxide compound which is brown in colour and the reaction can be shown as follows:
$2NO+{{O}_{2}}\to N{{O}_{2}}$
Hence due to the formation of nitrogen dioxide nitric oxide becomes brown.

Note:
Nitric acid is produced by the oxidation of ammonia represented by the chemical formula $N{{H}_{3}}$ at 750-900 C temperature and platinum is used as a catalyst in this reaction where we know that catalyst are those substances which do not take participation in the reaction but use just to increase the rate of reaction and this reaction by which nitric oxide also known as nitrogen oxide is prepared is known by the name ostwald's process.