if there are 19 grams of oxygen in a sample of aluminum oxide . how many grams of aluminium are present

Molecular Formula of (Aluminum Oxide) is Al2O3

Since the Molar Mass of Oxygen Atom = 16

Number of Moles (Atom) = Mass (Atom) / Molar Mass (Atom)

So, Number of Moles (Oxygen O3 Atom) = 19 / (16 * 3)
= 19 / 48
= 0.40 gm/mole

Molar Ratio of (Oxygen O3 Atom) = 0.40:3
Molar Ratio of (Aluminum Al2 Atom) = 0.27:2

Since, Number of Moles (Atom) = Mass (Atom) / Molecular Mass (Atom)

So, Mass (Atom) = Molar Mass (Atom) * Number of Moles (Atom)
Mass (Aluminum Al2 Atom) = 0.27 * (27 * 3)
= 0.27 * 81
= 21.87 gm

Because electrons have negligible mass, to account for the mass of the isotope, there must be 16 neutrons, 16 neutrally charged, massive, fundamental particles present in the sulfur nucleus. and thus finally, if we have the 32s2− ion, there are 18 electrons, 16 protons, and 16 neutrons.