Calculate the number of monochloro derivatives that formed when neo-pentane is chlorinated?

Options

A. 1
B. 2
C. 3
D. 4

Explanation

To calculate the number of monochloro derivatives that can form when neo-pentane is chlorinated, we first need to understand the structure of neo-pentane and how chlorination works.

### Step-by-Step Solution:

1. **Identify the Structure of Neo-pentane**:
Neo-pentane (also known as 2,2-dimethylpropane) has the following structure:
\[ \text{C} \quad \text{C} \quad \text{C} \quad \text{C} \]
\[ \text{CH}_3 \quad \text{CH}_3 \quad \text{CH}_3 \]
The central carbon is connected to two methyl groups and two other carbons.

2. **Understanding Chlorination**:
Chlorination of alkanes involves the substitution of hydrogen atoms with chlorine atoms. In the case of neo-pentane, we can replace one hydrogen atom with a chlorine atom.

3. **Identify Unique Hydrogen Atoms**:
In neo-pentane, we have:
- 2 hydrogen atoms on the central carbon (C)
- 6 hydrogen atoms on the three terminal methyl groups (CH3)

However, due to the symmetry of neo-pentane, not all hydrogen atoms are unique.

4. **Determine the Unique Monochloro Derivatives**:
- If we replace one of the hydrogen atoms from the central carbon (C), we get one unique product:
\[ \text{C} \quad \text{C} \quad \text{C} \quad \text{C} \]
\[ \text{CH}_2\text{Cl} \quad \text{CH}_3 \quad \text{CH}_3 \]
- If we replace one of the hydrogen atoms from the terminal methyl groups, we can replace any of the three CH3 groups, but they are all equivalent due to symmetry. Therefore, replacing any of these will yield the same product:
\[ \text{C} \quad \text{C} \quad \text{C} \quad \text{C} \]
\[ \text{CH}_3 \quad \text{CH}_2\text{Cl} \quad \text{CH}_3 \]

5. **Count the Unique Products**:
From the above analysis, we find:
- One unique product from chlorination at the central carbon.
- One unique product from chlorination at any of the terminal methyl groups.

Therefore, there are a total of **2 unique monochloro derivatives** formed when neo-pentane is chlorinated.

### Final Answer:
The number of monochloro derivatives formed when neo-pentane is chlorinated is **2**.