I believe its coal i hope this helped
Answer:
The answer is 4th one as I think
Answer:
A dimer (/ˈdaɪmər/) (di-, "two" + -mer, "parts") is an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent or intermolecular. The term homodimer is used when the two molecules are identical (e.g. A–A) and heterodimer when they are not (e.g. A–B).
Explanation:
1.atom 2.energy level 3.atomic number 4.compound 5.shell 6.electrons 7.molecule 8.atomic mass 9.neutrons 10.diatonic 11.proton
