Which of the following belong to the same homologous series?

Options

A. Ethane, ethene, ethyne
B. Propanol, propanone, propanal
C. Methanol, ethanol, propaol
D. Ethane, ethanol, ethanoic acid

Explanation

To determine which of the following compounds belong to the same homologous series, we need to follow these steps:

### Step 1: Understand the Concept of Homologous Series
A homologous series is a group of organic compounds that have the same functional group and differ from each other by a CH2 unit. This means that each successive compound in the series has one more carbon atom and two more hydrogen atoms than the previous one.

### Step 2: Identify the Functional Groups
To find out which compounds belong to the same homologous series, we first need to identify the functional groups of the given compounds. Compounds with the same functional group will belong to the same series.

### Step 3: Analyze the Given Compounds
Let's analyze the compounds mentioned:
1. **Methanol (CH3OH)** - This is an alcohol.
2. **Ethanol (CH3CH2OH)** - This is also an alcohol.
3. **Propanol (CH3CH2CH2OH)** - This is again an alcohol.

All three compounds have the same functional group (alcohol), which is -OH.

### Step 4: Check the Difference in Molecular Formula
Now, we need to check if the difference between the molecular formulas of these compounds is indeed a CH2 unit:
- Methanol (CH3OH) has a molecular formula of C1H4O.
- Ethanol (C2H6O) has a molecular formula of C2H6O.
- Propanol (C3H8O) has a molecular formula of C3H8O.

The differences are:
- From Methanol to Ethanol: C1 to C2 (difference of 1 carbon, which corresponds to CH2)
- From Ethanol to Propanol: C2 to C3 (again, a difference of CH2)

### Step 5: Conclusion
Since all three compounds (Methanol, Ethanol, and Propanol) have the same functional group and the difference between their molecular formulas is a CH2 unit, they belong to the same homologous series.

### Final Answer
The correct option is that Methanol, Ethanol, and Propanol belong to the same homologous series.

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