Check the box next to each formula that represents a substance that is a pure compound. co square Fe square H_(2)O+Mg square N_(2) square H_(2)O

A compound is a substance formed when two or more chemical elements are chemically bonded together. The key to identifying a compound is to look for more than one type of element in the formula. Let's examine each option:1. (Carbon Monoxide): This is a compound because it contains two different types of atoms - carbon and oxygen - chemically bonded together.2. (Iron): This is not a compound. It is an element because it consists of only one type of atom.3. : This is not a compound. It represents a mixture of two substances - water (a compound of hydrogen and oxygen) and Magnesium (an element). It's not a single compound because it has a "+" sign in between, indicating a mixture.4. (Nitrogen gas): This is not a compound. It is a molecule made up of two atoms of the same type - nitrogen. It doesn't contain atoms of different types, so it's not a compound.5. (Water): This is a compound. It is formed by a reaction between hydrogen and oxygen, both different atoms.In summary, a compound usually contains at least two different types of atoms chemically bonded together. If a formula includes only one type of atom, it is an element. If the formula has a "+" sign in between, it usually represents a mixture, not a single compound.