O Levels Chemistry (5070)•5070/11/M/J/25
Explanation
Molecular mass matching identifies the formula
Steps:
- Use atomic masses: C=12, H=1, O=16.
- Calculate A (C4H8O): 4×12 + 8×1 + 16 = 72.
- Calculate B (C3H8O): 3×12 + 8×1 + 16 = 60.
- Calculate C (C2H6O): 2×12 + 6×1 + 16 = 46.
- Compare to given M to find the match.
Why C is correct:
- C2H6O has molecular mass of 46, matching the compound's M per standard calculation for such organic formulas.
Why the others are wrong:
- A: Mass of 72 exceeds the given M.
- B: Mass of 60 exceeds the given M.
- D: Mass of 32 is below the given M.
Final answer: C
Topic: Formulae, functional groups and terminology
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