Answer: helium(He)
Explanation: Helium has only 2 electrons in the outermost energy level, but all of the other elements in its column have eight.
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).
~ I hope this helped, and I would appreciate Brainliest. ♡ ~ ( I request this to all the lengthy answers I give ! )
The theoretical yield is 160 g H₂O.
<em>Moles of H₂</em> = 18 g H₂ × (1 mol H₂/2.016 g H₂) = 8.93 mol H₂
<em>Moles of H₂O</em> = 8.93 mol H₂O × (2 mol H₂O/2 mol H₂) = 8.93 mol H₂O
<em>Theoretical yield</em> of H₂O = 8.93 mol H₂O × (18.02 g H₂O/1 mol H₂) = 160 g H₂O
I’m not sure if this is what you are referring to but there is something called a moles bridge which allows you to convert from one substance to another
Post the question so we can help