Question

The number of isomers (excluding geometrical isomers) for (A) is:

Answer 1

DBU of the given compound comes out to be 5. From the reaction given, it can be seen that the benzene ring (DBU = 4) is present in the starting compound and $B{r}_2/CC{l}_4$ addition is not happening means the possibilities of double bond and triple bond are eliminated. Hence the starting compound has some cyclic part (DBU = 1) attached with benzene.
Hence the following are the possible isomers:

Since (V) will not produce phthalic acid upon oxidation. So a total of 5 isomers are possible.