Which substance is a compound iron or nitrogen oxide

Nitrogen oxide is compound.

Explanation:

Compound is defined as chemical substance made up two or more than two different elements. For example : NaOH is the compound made up of 1 sodium atom, 1 oxygen atom and 1 hydrogen atom.

Now, according to the question, out iron and nitrogen oxide. Nitrogen dioxide (NO)is a compound because its made up of one nitrogen atom and 1 oxygen atom.

Where as iron is not a compound because it is just composed of iron atoms only.

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a