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Reviewed CSCA Chemistry question · Easy

How many moles of oxygen atoms are present in 0.250 mol of potassium permanganate, KMnO4?

  1. 0.250 mol
  2. 1.00 mol
  3. 0.500 mol
  4. 2.00 mol
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Correct answer

B. 1.00 mol

Principle or equation

The chemical formula indicates the number of atoms of each element per formula unit. For KMnO4, there are 4 oxygen atoms per formula unit.

Why this answer is correct

Multiply the number of moles of the compound by the number of oxygen atoms per formula unit: 0.250 mol × 4 = 1.00 mol of oxygen atoms.

Example

For 0.300 mol of Na2SO4, moles of oxygen atoms = 0.300 × 4 = 1.20 mol.

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