Question

How can you not distinguish between Vicinal and Geminal dihalides?

Answer 1

Hint: We know that the organic compounds in which two halogens are attached to the same carbon atom are known as Geminal dihalides. Gem means attached to the same atom and halide are the general term for halogens.

Complete answer:
The main difference between geminal dihalide and vicinal dihalides is that geminal dihalides have both halide groups attached to the same carbon atom of the compound whereas vicinal dihalides have two halide groups which are attached to two adjacent carbon atoms in the same compound.
Both give the same product (alkene) on reaction with alcoholic \[KOH.\] Gem dihalide: When the two halogen atoms are attached to the same carbon atom and are prepared by the addition reaction of vinyl halide, when vinyl halide undergoes an additional reaction with hydrogen chloride, then the formation of geminal dihalide takes place. Vicinal dihalide: When the two halogen atoms are on adjacent carbon atoms and are prepared by the reaction between a halogen and an alkene. Gem dihalide or vicinal dihalide gives alkene on treating with alcoholic \[KOH.\]
The word gem dihalide is an abbreviation for geminal dihalide. Geminal word in chemistry is derived from a Latin word ‘Gemini’ which means ‘twins’ which refers to the relationship between two atoms or functional groups which are attached to the same atoms. The common name for geminal dihalide is alkylidene halides

Note:
Remember that you may get confused between geminal dihalide and vicinal dihalides. The geminal dihalides are organic compounds containing two halide groups attached to the same carbon whereas vicinal dihalides are organic compounds having two halide groups attached to two adjacent carbon atoms of the same chemical compound. The terms ‘geminal’ and ‘vicinal’ are used for chemical compounds having substituents.