Which of the following alkyl halides is a secondary alkyl halide?

• A. ${\mathrm{CH}}_3\mathrm{CH}{\mathrm{CH}}_2\mathrm{Cl}$
• B. ${\mathrm{CH}}_3\mathrm{CH}\mathrm{Cl}{\mathrm{CH}}_3$
• C. ${\mathrm{CH}}_3\mathrm{CH}{\mathrm{CH}}_3\mathrm{Cl}$
• D. ${\mathrm{CH}}_3\mathrm{Cl}$

Answer: (B)

Verified step by step guidance

1. Recall that an alkyl halide is classified as primary, secondary, or tertiary based on the number of alkyl groups attached to the carbon bearing the halogen atom.
2. Identify the carbon atom bonded to the halogen (Cl) in each given structure.
3. Count the number of carbon atoms directly attached to this carbon bearing the halogen:
4. - If it is attached to one other carbon, it is a primary alkyl halide.
5. - If it is attached to two other carbons, it is a secondary alkyl halide.
6. - If it is attached to three other carbons, it is a tertiary alkyl halide.
7. Apply this rule to each option to determine which one has the halogen attached to a carbon bonded to exactly two other carbons, indicating a secondary alkyl halide.