Compound containing which of the following group can not show metamerism :-

Options

A. `-NH-`
B. `-O-`
C. `-overset(O)overset(||)C-O-`
D. `-overset(O)overset(||)C-OH`

Answer

To determine which functional group cannot show metamerism, we need to understand the concept of metamerism and the conditions required for it to occur.

### Step-by-Step Solution:

1. **Understanding Metamerism**:
Metamerism is a type of isomerism that occurs in compounds with the same molecular formula but different structural arrangements due to the presence of bivalent (or polyvalent) functional groups. This means that the functional group must be able to attach to different carbon chains on either side.

2. **Identifying Functional Groups**:
We will analyze each of the given functional groups to see if they can exhibit metamerism.

- **Option A: Amine Group (R-NH-R')**:
- The amine group is bivalent as it can attach to two different carbon chains (R and R').
- Therefore, it can show metamerism.

- **Option B: Ether Group (R-O-R')**:
- The ether group is also bivalent as it can connect two different carbon chains (R and R').
- Thus, it can also show metamerism.

- **Option C: Ester Group (R-C(=O)-O-R')**:
- The ester group is bivalent as well, allowing for different carbon chains on either side of the functional group.
- Therefore, it can show metamerism.

- **Option D: Carboxylic Acid Group (R-C(=O)-OH)**:
- The carboxylic acid group is a terminating group. It can only attach to the terminal carbon of a carbon chain, making it monovalent.
- Since it cannot attach to different carbon chains on either side, it does not show metamerism.

3. **Conclusion**:
Based on the analysis, the functional group that cannot show metamerism is the carboxylic acid group.

### Final Answer:
**The compound containing the carboxylic acid group (Option D) cannot show metamerism.**

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