Toluene is not soluble in water. Which of the following is most likely the formula of toluene?

• A. C2H5OH
• B. C6H6
• C. CH3COOH
• D. C7H8

Answer: (D)

Verified step by step guidance

1. Understand the concept of solubility: Substances that are polar or can form hydrogen bonds tend to be soluble in water, which is a polar solvent. Nonpolar substances are generally insoluble in water.
2. Analyze the given formulas: C2H5OH (ethanol) is polar and can hydrogen bond, so it is soluble in water. CH3COOH (acetic acid) is also polar and can hydrogen bond, so it is soluble in water. C6H6 (benzene) is nonpolar and not very soluble in water.
3. Recall the structure of toluene: Toluene is a methyl-substituted benzene ring, which means it has the formula C7H8 (C6H5CH3). It is nonpolar and thus not soluble in water.
4. Compare the given options with the known formula of toluene: None of the options exactly match C7H8, but the problem states the correct formula is C7H8, which corresponds to toluene.
5. Conclude that toluene's insolubility in water is due to its nonpolar nature and that its molecular formula is C7H8, consistent with a benzene ring plus a methyl group.