The common name and IUPAC name of the following compound, respectively, are
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → o-Toluidine and 2-Methylaniline
The compound is a benzene ring carrying an –\( \ce{NH2} \) group and, on the next carbon, a –\( \ce{CH3} \) group. The methylanilines have the common name toluidine, with o-, m- or p- to show where the methyl group is. In the IUPAC system the parent is aniline (also an accepted IUPAC name; benzenamine), the carbon bearing –\( \ce{NH2} \) is C1, and the methyl group gets a number.
Here the methyl group is on the carbon next to the –\( \ce{NH2} \) carbon: the ortho position, C2. So the common name is o-toluidine and the IUPAC name is 2-methylaniline (2-methylbenzenamine).
Why the other options are incorrect
Option (1) Aniline and 2-methylaniline — Incorrect. Aniline is \( \ce{C6H5NH2} \) itself, with no methyl group; it cannot be the common name of this compound.
Option (3) o-Toluidine and Benzenamine — Incorrect. The common name is right, but benzenamine is the IUPAC name of aniline; it leaves out the methyl group.
Option (4) m-Toluidine and Benzenamine — Incorrect. m-Toluidine has the methyl group at C3 (3-methylaniline), and benzenamine is aniline.
NCERT (2026-27 edition):
Nomenclature – …
