Which of the following statements is not correct?

Options

A. A common functional group is present in different members of a homologous series.
B. Two consecutive members of a homologous series differ by a `-CH_(3)` group.
C. The members of a homologous series can be represented by one general formula.
D. Different members of a homologous series have similar chemical properties.

Explanation

To determine which statement is not correct regarding homologous series, let's analyze the statements one by one based on the information provided:

1. **Statement 1**: "The common functional group is present in different members of the homologous series."
- This statement is **correct**. Members of a homologous series share a common functional group, which is responsible for their similar chemical properties.

2. **Statement 2**: "Two consecutive members differ by CH3 group."
- This statement is **not correct**. In a homologous series, two consecutive members actually differ by a CH2 unit, not a CH3 group. For example, if we take methane (CH4) and ethane (C2H6), the difference is CH2 (which is -CH2).

3. **Statement 3**: "Members of the homologous series can be represented by one formula."
- This statement is **correct**. Members of a homologous series can indeed be represented by a general formula, such as CnH2n+2 for alkanes.

4. **Statement 4**: "Different members of the homologous series have similar chemical properties."
- This statement is **correct**. Due to the presence of the same functional group, different members of a homologous series exhibit similar chemical properties.

**Conclusion**: The statement that is not correct is **Statement 2**: "Two consecutive members differ by CH3 group."