Among the three isomeric dichlorobenzenes , which has the highest boiling point and highest melting point ?

Explanation

To determine which isomer of dichlorobenzene has the highest boiling point and the highest melting point, we need to analyze the three isomers: ortho-dichlorobenzene, meta-dichlorobenzene, and para-dichlorobenzene.

### Step 1: Understanding the Isomers
Dichlorobenzene has three isomers based on the positions of the chlorine atoms on the benzene ring:
- **Ortho-dichlorobenzene**: Chlorine atoms are adjacent to each other (1,2-dichlorobenzene).
- **Meta-dichlorobenzene**: Chlorine atoms are separated by one carbon atom (1,3-dichlorobenzene).
- **Para-dichlorobenzene**: Chlorine atoms are opposite each other (1,4-dichlorobenzene).

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