Calculate the percentage by mass of O in CuSO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)

Answer and explanation

Correct answer: C. 40.1%

  1. Step 1: of CuSO .
  2. Step 2: Mass of O in one formula unit .
  3. Step 3: Percentage .
Answer
40.1%.
Why not the others: 10%: the number of atoms in the formula is ignored. 59.9%: that is the percentage of all the other elements.

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