Match Structure with their Common Name
| List I | List-II |
| Structure | Common Name |
(A)  | (I) Allyl chloride |
(B)  | (II) Ethylene dichloride |
(C)  | (III) Vinyl chloride |
(D)  | (IV) Ethylidene chloride |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) - (III), (B) - (IV), (C) - (II), (D) - (I)
Common names of halides name the group attached to the halogen, followed by “chloride”, “bromide” ...:
Vinyl = CH2=CH– (halogen on a C=C carbon); allyl = CH2=CH–CH2– (halogen on the carbon next to the C=C).
Dihalides with both halogens on the same carbon (gem-dihalides) are named as alkylidene halides; those with the halogens on adjacent carbons (vic-dihalides) are named as alkylene dihalides.
(A) CH2=CH–Cl — This matches (III) Vinyl chloride. The Cl atom is on a carbon of the C=C double bond, so the group is vinyl. IUPAC name: chloroethene.
(B) CH3–CHCl2 — This matches (IV) Ethylidene chloride. Both Cl atoms are on the same carbon of an ethane chain, so it is a gem-dihalide, named as an alkylidene halide. IUPAC name: 1,1-dichloroethane.
(C) ClCH2–CH2Cl — This matches (II) Ethylene dichloride. The two Cl atoms are on adjacent carbons, so it is a vic-dihalide, named as an alkylene dihalide. IUPAC name: 1,2-dichloroethane.
(D) CH2=CH–CH2–Cl — This matches (I) Allyl chloride. The Cl atom is on the CH2 carbon next to the C=C (an allylic carbon), so the group is allyl. IUPAC name: 3-chloropropene.
NCERT (2026-27 edition):
Nomenclature – “The dihaloalkanes having the same type of halogen atoms are named as alkylidene or alkylene dihalides. The dihalo-compounds having both the halogen atoms are further classified as geminal halides or gem-dihalides when both the halogen atoms are present on the same carbon atom of the chain and vicinal halides or vic-dihalides when halogen atoms are present on adjacent carbon atoms. In common name system, gem-dihalides are named as alkylidene halides and vic-dihalides are named as alkylene dihalides. In IUPAC system, they are named as dihaloalkanes.”
Table 6.1 (part):
| Structure | Common name | IUPAC name |
|---|---|---|
| CH2 = CHCl | Vinyl chloride | Chloroethene |
| CH2 = CHCH2Br | Allyl bromide | 3-Bromopropene |