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Reviewed CSCA Chemistry question · Easy

What is the total number of oxygen atoms in 0.250 mol of potassium sulfate, K2SO4? (Avogadro constant = 6.02 × 10^23 mol^-1)

  1. 1.51 × 10^23
  2. 3.01 × 10^23
  3. 6.02 × 10^23
  4. 1.20 × 10^24
Show the answer and explanation

Correct answer

C. 6.02 × 10^23

Principle or equation

Each formula unit of K2SO4 contains 4 oxygen atoms. Number of O atoms = moles × 4 × Avogadro constant.

Why this answer is correct

0.250 mol × 4 = 1.00 mol O atoms. 1.00 mol × 6.02 × 10^23 = 6.02 × 10^23 atoms.

Example

For 0.100 mol Na2SO4, O atoms = 0.100 × 4 × 6.02e23 = 2.41e23.

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