Answer
Understanding the Position Numbering on Benzene Rings
- In benzaldehyde, the carbon bearing the aldehyde group (–CHO) is always position 1.
- When another substituent (like Cl) is attached, its position is numbered relative to the –CHO group.
- If Cl is at position 2 (adjacent to the –CHO), the compound is referred to using the prefix “ortho” (o-).
- So, 2-chlorobenzaldehyde = o-chlorobenzaldehyde
Therefore, 2-chlorobenzaldehyde is also known as o-chlorobenzaldehyde.
Correct Option:
Option C: o-chlorobenzaldehyde