How many moles are there in 25 g of CaCO₃? (Relative atomic masses: H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Zn = 65.)
Answer and explanation
Correct answer: D. 0.25 mol
- Step 1: Molar mass of CaCO₃ = 100 g/mol.
- Step 2: mol.
Answer
0.25 mol.
Why not the others: 2500 mol: the mass was multiplied by the molar mass instead of divided. 4 mol: the ratio was inverted. 25 mol: the mass was used as the number of moles.
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