Answer:
Atoms are at their most stable when their outermost energy level is either empty of electrons or filled with electrons.
Those are called isotopes,
the answer is 3.
each element has its own unique number of protons (atomic number) but a different number of neutrons can be shown in example number 3.
1) As for its chemical composition, coal is a mixture of high-molecular-weight polycyclic aromatic compounds, such as benzene C6H6, toluene C6H5CH3, xylene C6H4(CH3)2, naphthalene C10H8, anthracene C14H10, pyrene C16H10 and their derivatives with high mass fraction of carbon, as well as of water and volatile substances.
2) The coal asphaltenes have a relatively narrow MWD (full width ≈ 150 amu) with an average molecular weight of ≈340 amu. The petroleum asphaltenes display a broader MWD (full width ≈ 300 amu) and are heavier on average (≈680 amu).
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Diffusion is a process that results from the random motion of molecules and results in a net movement of matter from a high-concentration region to a low-concentration zone.