Final answer:
None of the options provided (2-chlorohexane, 3-chlorohexane, 4-chlorohexane, 5-chlorohexane) match the criteria of the compound not reacting with sodium methoxide, as all are secondary chlorides and would normally undergo substitution. The question likely contains an error or requires additional clarification.
Step-by-step explanation:
The student is dealing with isomers of alkanes substituted with chlorine (haloalkanes). We know that compound X has a molecular formula of C9H19Cl and does not react with sodium methoxide, which suggests it is not an allylic or benzylic halide (which would be more reactive towards nucleophiles like methoxide).
Considering the molecular formula C9H19Cl, and since the compound is not undergoing substitution with sodium methoxide, it implies the chlorine atom is not positioned on a secondary or tertiary carbon, which would be more reactive. The possible structures of chlorohexane (C6H13Cl) that comply with this would be 1-chlorohexane or 2-chlorohexane. However, neither of these options are provided in the choices given (A) through (D). If we include the possibility of there being more than one alkyl chain attached to the chlorine-containing carbon, then the structure could be more complex and still not react with sodium methoxide.
Therefore, the information given seems to be contradictory or incomplete since none of the choices A, B, C, or D match the requirement stated in the question. All four options given would normally react with sodium methoxide to give substitution products as they are all secondary chlorides. The student may require additional information or clarification to correctly identify the compound.