Toluene is most readily Sulphonate because of the electron releasing group attach to it neucleophilicity increases resulting in a fast attack to during sulphonation. Among these methyl group is electron donating, activate benzene ring for electrophilic aromatic substitution.
So option " C " is correct answer.

Sulphonation is a chemical reaction in which a sulfonyl group (-SO3H) is added to a molecule. It is an important reaction in organic chemistry and is commonly used to introduce sulfonic acid groups into organic compounds. The compound that can be most readily sulphonated among the given options is Toluene.

Explanation:

Benzene: Benzene is a highly stable aromatic compound. It has a delocalized pi electron system, which provides stability to the molecule. The delocalization of electrons makes it difficult for benzene to undergo electrophilic substitution reactions, including sulphonation. Therefore, benzene is not readily sulphonated under normal conditions.

Nitrobenzene: Nitrobenzene is an aromatic compound containing a nitro group (-NO2). The presence of the nitro group makes it more electron-withdrawing, which increases the reactivity of the benzene ring towards electrophilic substitution reactions. However, the presence of the nitro group also makes the molecule less reactive towards sulphonation. This is because the nitro group is a strong deactivating group, which reduces the electron density on the benzene ring and hinders the attack of the sulfonyl group.

Toluene: Toluene is a methyl-substituted benzene compound. The presence of the methyl group increases the electron density on the benzene ring, making it more reactive towards electrophilic substitution reactions. Toluene can readily undergo sulphonation because the methyl group activates the benzene ring towards electrophilic attack, making it more susceptible to sulfonylation.

Chlorobenzene: Chlorobenzene is an aromatic compound containing a chlorine atom attached to the benzene ring. The presence of the chlorine atom does not significantly affect the reactivity of the benzene ring towards sulphonation. Chlorobenzene is less reactive than toluene towards sulphonation because the chlorine atom is a weaker activating group compared to the methyl group.

In conclusion, among the given options, toluene is the compound that can be most readily sulphonated. Its reactivity is enhanced by the presence of the methyl group, which activates the benzene ring towards electrophilic attack.