Question

which is a force that holds atoms together?
chemical bond
electron shell
valence electron
chemical formula

Explanation:

A chemical bond is the force that holds atoms together in molecules or compounds. An electron shell is a region of space where electrons orbit an atom's nucleus, a valence electron is an outer-shell electron involved in bonding, and a chemical formula represents the composition of a compound—none of these are forces holding atoms together.

Answer:

A. chemical bond