On halogenation, an alkane gives only one monohalogenated product. The alkane may be:

Options

A. 2-methyl butane
B. 2, 2-dimethyl propane
C. cyclopentane
D. both (b) and (c)

Explanation

To solve the problem of identifying which alkane gives only one monohalogenated product upon halogenation, we can analyze the provided options step by step.

### Step 1: Understand the concept of halogenation
Halogenation of alkanes involves the substitution of hydrogen atoms with halogen atoms (like chlorine or bromine). The key point is that if an alkane has multiple equivalent hydrogen atoms, it can lead to the formation of more than one product.

### Step 2: Analyze the options
We need to evaluate each option to see if it can produce only one unique monohalogenated product.

#### Option A: 2-Methylbutane
1. **Structure**: The structure of 2-methylbutane is:
```
CH3
|
CH3-CH-CH2-CH3
|
CH3
```
2. **Halogenation**: When we perform halogenation, we can replace any of the hydrogen atoms on the carbon atoms. Since there are multiple hydrogen atoms on different carbons, we can get different products. For example:
- Replacing a hydrogen on the first carbon gives one product.
- Replacing a hydrogen on the second carbon gives another product.
- Replacing a hydrogen on the third carbon gives yet another product.

Thus, multiple products can be formed. Therefore, option A does not satisfy the condition.

#### Option B: 2,2-Dimethylpropane
1. **Structure**: The structure of 2,2-dimethylpropane is:
```
CH3
|
CH3-C-CH3
|
CH3
```
2. **Halogenation**: In this case, there are no unique hydrogen atoms to replace. Any substitution will lead to the same product:
- Replacing any of the hydrogen atoms on the central carbon will yield the same monohalogenated product.

Therefore, only one unique product is formed. Option B satisfies the condition.

#### Option C: Cyclopentane
1. **Structure**: The structure of cyclopentane is:
```
CH2
/ \
CH2 CH2
| |
CH2------CH2
```
2. **Halogenation**: When we perform halogenation on cyclopentane, any hydrogen atom can be replaced:
- Replacing any hydrogen on any carbon will yield the same product due to symmetry.

Thus, only one unique product is formed. Option C also satisfies the condition.

#### Option D: Other options (not provided)
Since we have already analyzed options A, B, and C, we can conclude that both B and C are valid answers.

### Conclusion
The alkanes that give only one monohalogenated product upon halogenation are:
- **2,2-Dimethylpropane (Option B)**
- **Cyclopentane (Option C)**

### Final Answer
The alkane may be: **2,2-Dimethylpropane or Cyclopentane.**

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