Sulphonation of chlorobenzene gives

o-and p-chloro benzene sulphonic acid

The correct answer is option 4. o-and p-chloro benzene sulphonic acid.

Sulphonation of chlorobenzene typically results in the formation of a mixture of o- and p-chlorobenzene sulphonic acids. Chlorobenzene can undergo sulphonation, where a sulphonyl group \((-SO_3H)\) is added to the benzene ring under acidic conditions. The sulphonation reaction introduces the sulphonyl group at either the ortho \((o-)\) or para \((p-)\) positions relative to the chlorine atom on the benzene ring.

o-Chlorobenzene sulphonic acid: This is formed when the sulphonyl group attaches to the benzene ring at the position adjacent to the chlorine atom.

p-Chlorobenzene sulphonic acid: This is formed when the sulphonyl group attaches to the benzene ring opposite to the chlorine atom.

Due to the electron-withdrawing nature of the chlorine substituent, the benzene ring becomes more reactive towards electrophilic substitution reactions like sulphonation. However, the exact distribution between o- and p-isomers in the sulphonation of chlorobenzene can vary and is typically influenced by reaction conditions such as temperature and concentration.

Conclusion: When chlorobenzene undergoes sulphonation, the product typically consists of a mixture of o- and p-chlorobenzene sulphonic acids. Therefore, the correct answer is: o- and p-chlorobenzene sulphonic acid