To determine the number of moles of oxygen in one mole of Al₂(SO₄)₃, we need to examine the chemical formula of the compound.
The compound Al₂(SO₄)₃ contains two aluminum ions (Al²⁺) and three sulfate ions (SO₄²⁻). Each sulfate ion consists of one sulfur atom (S) and four oxygen atoms (O). Therefore, the total number of oxygen atoms in the compound is 3 (sulfate ions) × 4 (oxygen atoms per sulfate ion) = 12 oxygen atoms.
Since there are 12 oxygen atoms in one mole of Al₂(SO₄)₃, there are also 12 moles of oxygen atoms in one mole of Al₂(SO₄)₃.