Answer:
and
are the compounds.
Step-by-step explanation:
A chemical compound is defined as a chemical substance that is formed by the combination of two or more atoms of different elements which cannot be separated by any physical means but when chemically treated, they decompose into their parent elements.
For example, water is made up of hydrogen and oxygen. This compound is a liquid and its individual components are gases. When water is decomposed, it forms hydrogen and oxygen gas.
For the given options:
He(Helium) is an element formed by the combination of only type of atoms.
and
are molecules of same element.
is a compound fomed by the combination of iron and oxygen atoms.
is a compound fomed by the combination of carbon, hydrogen, and oxygen atoms.
Hence,
and
are the compounds.