How many isomers have the name bromomethylcyclopentane ? (ignoring chirality)

Options

A. 4
B. 5
C. 6
D. 7

Explanation

To determine how many isomers can be formed from the name "bromomethylcyclopentane," we need to analyze the structure and possible variations.

### Step-by-Step Solution:

1. **Identify the Base Structure**:
- The base structure is cyclopentane, which is a five-membered carbon ring.

2. **Identify the Substituents**:
- The name indicates that there is a bromomethyl group (-CH2Br) attached to the cyclopentane ring.

3. **Determine Possible Positions for Substitution**:
- In cyclopentane, there are five carbon atoms where the bromomethyl group can be attached. However, due to the symmetry of the cyclopentane ring, some positions will yield the same isomer.

4. **Consider the Different Isomeric Forms**:
- When the bromomethyl group is attached to different carbon atoms in the ring, we need to consider the unique arrangements.
- The bromomethyl group can be attached to each of the five carbon atoms, but because of the cyclic nature and symmetry of the cyclopentane, some of these will be identical.

5. **Count the Unique Isomers**:
- For cyclopentane with a bromomethyl group, the unique isomers can be identified as follows:
- Bromomethyl at position 1 (C1)
- Bromomethyl at position 2 (C2)
- Bromomethyl at position 3 (C3)
- Bromomethyl at position 4 (C4)
- Bromomethyl at position 5 (C5)
- However, due to the ring's symmetry, the isomers at positions 1 and 4 are identical, as are those at positions 2 and 5, and those at positions 3.

6. **Final Count of Isomers**:
- Therefore, the unique isomers are:
- C1 (or C4)
- C2 (or C5)
- C3
- This results in a total of **3 unique isomers** of bromomethylcyclopentane.

### Final Answer:
There are **3 isomers** of bromomethylcyclopentane (ignoring chirality).