Which of the following statements is/are true about a homologous series :-

Options

A. Different homologous series may have same general formula
B. Alkane homologous series have `C_(n)H_(2n)` general formula
C. Homologues have same physical but different chemical properties
D. All of them

Answer

To determine which statements about a homologous series are true, we will analyze each statement based on the characteristics of homologous series in organic chemistry.

### Step-by-Step Solution:

1. **Understanding Homologous Series**:
- A homologous series is a group of organic compounds that have a similar general formula, similar chemical properties, and differ from each other by a constant unit, typically a -CH2- group.

2. **Analyzing the Statements**:
- **Statement 1**: "Different homologous series may have the same general formula."
- This statement is true. For example, aldehydes and ketones are different homologous series but can have the same general formula (C_nH_2nO).

- **Statement 2**: "Alkane homologous series have the formula C_nH_2n."
- This statement is false. The correct general formula for alkanes is C_nH_(2n+2). For instance, for n=1 (methane), the formula is CH_4, which fits C_nH_(2n+2).

- **Statement 3**: "Homologues may have the same physical but different chemical properties."
- This statement is also false. Members of a homologous series generally have similar chemical properties due to their similar functional groups, although they may differ in physical properties like boiling and melting points.

3. **Conclusion**:
- Based on the analysis, only Statement 1 is true. Therefore, the correct answer is that only the first statement is true.

### Final Answer:
- The true statement about a homologous series is: **Only Statement 1 is true.**

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