Which of the following represent correct pair of homologous ?

Options

A.
B. `MeOH` and `MeCH_(2)CH_(2)OH`
C.
D.

Answer

To determine which pairs represent correct homologous series, we need to analyze the given options. Homologous series are groups of organic compounds that differ by a constant unit, typically a -CH2- group, and have similar chemical properties.

### Step-by-Step Solution:

1. **Identify the Options**: We have four pairs of compounds to analyze. Let's denote them as A, B, C, and D.

2. **Analyze Option A**:
- The first compound is a phenol (with an OH group directly attached to a benzene ring).
- The second compound is a primary alcohol (with an OH group attached to a saturated carbon).
- **Conclusion**: These two compounds are not homologous because they belong to different functional groups and have different chemical properties.

3. **Analyze Option B**:
- The first compound is methanol (CH3OH).
- The second compound is ethylene glycol (MECH2CH2OH).
- **Conclusion**: These compounds can be part of a homologous series. Methanol can be considered the first member, and by adding a -CH2- group, we can derive the next member (ethylene glycol). Thus, this pair is homologous.

4. **Analyze Option C**:
- The first compound is an ester (HC=OCH2).
- The second compound is another ester (C=OCH2).
- **Conclusion**: These compounds differ by a -CH2- group and belong to the same functional group (esters). Therefore, this pair is also homologous.

5. **Analyze Option D**:
- The first compound is a primary amine (CH3CH2NH2).
- The second compound is a secondary amine (CH3CH2NHCH3).
- **Conclusion**: These compounds are different classes of amines and do not represent a homologous series since they differ by more than just a -CH2- group.

6. **Final Conclusion**: The correct pairs of homologous series are B and C.

### Final Answer:
The correct pairs of homologous series are **B and C**.