Gas a Is Composed of Diatomic Molecules (Two Atoms Per

Gas A is composed of diatomic molecules (two atoms per molecule) of a pure element. Gas B is composed of triatomic molecules (three atoms per molecule) of another pure element. A volume of gas B is found to be three times more massive than an equal volume of gas A. How does the mass of an atom of gas B compare with the mass of an atom of gas A?

A) An atom of gas B is six times the mass of an atom of gas A.
B) An atom of gas B is three times the mass of an atom of gas A.
C) An atom of gas B is two times the mass of an an atom of gas A.
D) An atom of gas B is equivalent to the mass of an atom of gas A.