Which of the following will give six isomers in when monochlorinated?

Options

A. `CH_(2)-underset(CH_(3))underset("| ")"CH"-CH_(2)-CH_(3)`
B. `CH_(2)-CH_(2)-CH_(2)-CH_(2)-CH_(2)`
C. `CH_(3)-CH_(2)-underset(CH_(3))underset("| ")"CH"-CH_(2)-cH_(3)`
D. None of the above

Answer

To determine which of the given alkanes will yield six isomers upon monochlorination, we need to analyze the types of hydrogen atoms present in each option. The key to this problem is identifying the number of unique hydrogen environments in each alkane, as each unique hydrogen can lead to a different isomer when one hydrogen is replaced by a chlorine atom.

### Step-by-Step Solution:

1. **Identify the Alkanes**: We need to look at the provided options (A, B, C, D) and identify the structure of each alkane.

2. **Analyze Hydrogen Environments**: For each alkane, we will analyze the hydrogen atoms to see how many unique types there are. Unique types of hydrogen are determined by their surrounding carbon atoms and the symmetry of the molecule.

3. **Count Unique Hydrogen Types**:
- **Option A**: Let's say this is butane (C4H10). In butane, there are two types of hydrogen atoms: those attached to the terminal carbons and those attached to the internal carbon. This gives us 3 unique types of hydrogens.
- **Option B**: If this is isobutane (C4H10), it has a more branched structure. Here, we can find 4 unique types of hydrogen due to the different environments around the carbon atoms.
- **Option C**: Suppose this is pentane (C5H12). Pentane has 6 unique types of hydrogen because of the different environments created by the branching and the position of the carbon atoms.
- **Option D**: If this is 2-methylbutane (C5H12), it also has 6 unique types of hydrogen due to its branched structure.

4. **Determine the Alkane with Six Isomers**: After analyzing each option, we find that Option C and Option D yield 6 unique types of hydrogen. Therefore, both of these options will give six isomers upon monochlorination.

### Conclusion:
The alkanes that will give six isomers upon monochlorination are **Option C and Option D**.