Two geometrical isomers are possible for the following compound

To solve this, let's analyze each compound in detail to determine if two geometric isomers are possible.

1. Ethylidene Bromide (C2H4Br2):

   • This compound has two bromine atoms attached to an ethylidene group (C2H4).
   • The carbon atoms are double-bonded to each other (C=C).
   • The possible geometric isomers for such a compound arise when there are different groups attached to the carbon-carbon double bond.
   • In this case, you can have cis and trans isomers (also called E and Z configurations) depending on the positions of the bromine atoms relative to the ethyl group.

   Answer: Two geometric isomers (cis and trans).

2. Acetylene Tetrachloride (C2H2Cl4):

   • Acetylene has a C≡C triple bond, and each carbon atom is attached to two chlorine atoms (Cl) and a hydrogen atom (H).
   • Since the carbons are triple-bonded, they cannot rotate around the bond, so no cis/trans isomerism is possible here.

   Answer: No geometric isomers are possible.

3. Ethylene Dichloride (C2H4Cl2):

   • Ethylene dichloride has two chlorine atoms attached to an ethylene (C=C) group.
   • Like ethylidene bromide, this compound can have cis and trans isomerism based on the position of the chlorine atoms relative to each other across the double bond.

   Answer: Two geometric isomers (cis and trans).

4. Acetylene Dibromide (C2H2Br2):

   • Acetylene dibromide consists of a C≡C triple bond with bromine atoms attached to each carbon atom.
   • Since the triple bond does not allow rotation and there are no groups that can lead to different spatial arrangements, no cis/trans isomerism is possible.

   Answer: No geometric isomers are possible.