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.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6