Empirical formula from mass percentages

Steps:

• Assume 100 g sample for simplicity.
• Calculate moles: C = 30/12 = 2.5 mol; H = 3.8/1 = 3.8 mol; O = 20/16 = 1.25 mol; Cl = 46/35.5 ≈ 1.30 mol.
• Divide by smallest moles (1.25): C = 2.0; H ≈ 3.0; O = 1.0; Cl ≈ 1.0.
• Ratio gives CH₃OCl as empirical formula.

Why A is correct:

• Mole ratio C:H:O:Cl = 2:3:1:1 matches calculated values from percentages.

Why the others are wrong:

• B: Lacks Cl, ignoring 46% Cl present.
• C: Shows H₂ ratio, but calculation gives H₃.
• D: Lacks O, ignoring 20% O; also implies two Cl atoms, mismatching Cl mole ratio.

Final answer: A