Question

The number of possible isomers of the compound with molecular formula $C_7H_8 O$ is

• A. 3
• B. 5
• C. 7
• D. 9

Answer 1

The Correct Option is B

The problem requires us to determine the number of possible isomers for a compound with the molecular formula \(C_7H_8O\). This compound could form structural isomers, including position isomers and functional group isomers.

To solve this, we need to identify all possible isomeric structures for this formula. The compound \(C_7H_8O\) typically denotes a derivative of a benzene ring (aromatic compound), as the hydrocarbon part can be seen as structural components in benzene derivatives.

1. Plausible structures: Since the formula is \(C_7H_8O\), one common family of compounds is phenols that retain an aromatic ring and have substitutions on the benzene ring.
   • C_6H_5 is the phenyl ring configuration with potential substitutions.
   • Common derivatives include phenols, arenes with methoxy groups, and benzylic alcohols.
2. Types of isomers:
   1. Structural isomers: Diferent connectivity of atoms can give rise to ketones, alcohols, and ethers as functional group isomers.
   2. Positional isomers: In case of aromatic compounds, positions ortho (1,2-), meta (1,3-), and para (1,4-) on the benzene ring give rise to different isomers for hydroxyl or methoxy substitution.
      • For a phenolic group, we achieve: o-cresol, m-cresol, and p-cresol isomers.
      • For methoxy group derivatives, similar ortho, meta, and para isomers will arise with methoxybenzene derivation.
3. Counting isomers: Each distinct structure or position counts as a unique isomer.
   • Phenolic derivatives: o-cresol, m-cresol, p-cresol.
   • Methoxybenzene derivatives (Anisole isomers): Making methoxy substitutions yield matching ortho, meta, and para isomers.

Based on the above analysis, it is apparent that we have the following isomer types:

• o-cresol, m-cresol, p-cresol
• o-methoxybenzene, m-methoxybenzene

Thus, we have 5 distinct isomers. Therefore, the correct answer is 5.