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What is the approximate percentage of oxygen by mass in Al₂(SO₄)₃?
A56.1%
B57.7%
C53.1%
D52.6%
Answer & Solution
Correct answer: A. 56.1%
1. Molar mass: Al = 2×27 = 54, S = 3×32 = 96, O = 12×16 = 192. Total = 342.
2. Mass of oxygen = 192.
3. Percentage = 192 / 342 × 100 ≈ 56.1%.
_Source: RRB Group D CEN-02/2018 PYQ, Q.6._