Which list only includes terms that describe oxygen, gas, and O2? A. Compound, molecule, pure substance
B. Element, molecule, pure substance
C. Atom, compound, molecule
D. Atom, element, molecule

Oxygen gas O2 is a compound, a molecule and a pure substance.

Oxygen gas is a compound because it contains more than one atom( two oxygen atoms) that are chemically combined together.

Oxygen gas is a molecule because it can exist independently as a unit and the oxygen atoms are covalently bound.

It is a pure substance because it contains only oxygen molecules.

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number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.