Volume perhaps ?
Hope this helps !
Volume= Mass/ Density= 20/184
= 0.108 cubic cm
Isotope atoms mean, atoms with the same number of protons but different number of neutrons in their nuclei . The given oxygen atoms are isotopes meaning they have different number of neutrons in their nuclei . Oxygen 16 have 8 protons and 8 neutrons in its nucleus but Oxygen has 8 protons and 10 neutrons. That's what make them different.
The change of phase from a vapor to a liquid is called condensation.
Hope this helps~
