How many aromatic isomers are possible for trichlorobenzene `(C_(6)H_(3)Cl_(3))`?

Options

A. 2
B. 3
C. 4
D. 5

Answer

To determine how many aromatic isomers are possible for trichlorobenzene (C₆H₃Cl₃), we can follow these steps:

### Step 1: Understand the Structure of Benzene
Benzene is a six-carbon ring with alternating double bonds, which gives it aromatic properties. Each carbon in the benzene ring can bond with one hydrogen atom or a substituent.

### Step 2: Identify the Substituents
In trichlorobenzene, three chlorine atoms (Cl) are substituents on the benzene ring, replacing three hydrogen atoms.

### Step 3: Determine Possible Positions for Chlorine Atoms
Chlorine atoms can be attached to different positions on the benzene ring. The positions are typically numbered as follows:
- Position 1: Carbon 1
- Position 2: Carbon 2
- Position 3: Carbon 3
- Position 4: Carbon 4
- Position 5: Carbon 5
- Position 6: Carbon 6

### Step 4: Consider the Different Isomeric Arrangements
We need to consider the different arrangements of the three chlorine atoms on the benzene ring. The possible arrangements are:
1. **1,2,3-Trichlorobenzene**: Chlorines are on adjacent carbons (positions 1, 2, and 3).
2. **1,2,4-Trichlorobenzene**: Chlorines are on positions 1, 2, and 4 (one chlorine is separated from the others).
3. **1,3,5-Trichlorobenzene**: Chlorines are on alternating carbons (positions 1, 3, and 5).

### Step 5: Count the Isomers
From the arrangements identified, we see that there are three distinct aromatic isomers of trichlorobenzene:
1. 1,2,3-Trichlorobenzene
2. 1,2,4-Trichlorobenzene
3. 1,3,5-Trichlorobenzene

### Conclusion
Thus, the total number of aromatic isomers possible for trichlorobenzene (C₆H₃Cl₃) is **three**.

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