Answer:
Diatomic molecules consist of two atoms bonded together. In contrast, monatomic elements consist of single atoms (e.g., Ar, He). Many compounds are diatomic, such as HCl, NaCl, and KBr. Diatomic compounds consist of two different elements. There are seven pure elements that form diatomic molecules.
The answer to your proposed question is Neutron. This is because the atomic mass unit of a neutron is 1 and so it would contribute to the overall mass of the atom.
I hope this answer helped you!
V=84.0 mL = 84.0 cm³
m=609.0 g
p=m/v
p=609.0/84.0=7.25 g/cm³
You will need 1 moles. Hope this helps!!