How many structural isomers does xylene,C₆H₄(CH₃)₂,have?

Question

Quizplus · Accepted Answer

Xylene is a compound with two benzene rings that are directly bonded to each other. The substituent positions on each of the benzene rings are identical (1,2,3,and 4), meaning that they have the same connectivity. 
Thus the possible isomers are based on the positions where the -CH3 groups are attached. 
There are three possible isomers:
1) Ortho-xylene, where the -CH3 groups are attached at the 1,2 positions
2) Meta-xylene, where the -CH3 groups are attached at the 1,3 positions
3) Para-xylene, where the -CH3 groups are attached at the 1,4 positions

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How Many Structural Isomers Does Xylene,C₆H₄(CH₃)₂,have