Assertion (A): Following are the members of a homologous series :
`CH_(3) OH, CH_(3) CH_(2) OH, CH_(3) CH_(2) CH_(2) OH`
Reason (R): A series of compounds with same functional group but differing by ` - CH_(2) - ` unit is called a homologous series

Options

A. Both (A) and (R) are true and (R) is correct explanation of the assertion.
B. Both (A) and (R) are true and (R) not is correct explanation of the assertion.
C. (A) is true but (R) is false.
D. (A) is false but (R) is true.

Answer

To solve the question regarding the assertion and reason about the homologous series, we will break it down step by step.

### Step 1: Understand the Assertion
The assertion states that the following compounds are members of a homologous series:
- CH₃OH (Methanol)
- CH₃CH₂OH (Ethanol)
- CH₃CH₂CH₂OH (Propanol)

### Step 2: Identify the Functional Group
All three compounds have the same functional group, which is the hydroxyl group (-OH). This is a key characteristic of alcohols.

### Step 3: Check the Difference Between Consecutive Compounds
To determine if these compounds belong to a homologous series, we need to check if they differ by a -CH₂- unit:
- The difference between CH₃OH and CH₃CH₂OH:
- CH₃CH₂OH - CH₃OH = CH₂
- The difference between CH₃CH₂OH and CH₃CH₂CH₂OH:
- CH₃CH₂CH₂OH - CH₃CH₂OH = CH₂

Since both pairs of consecutive compounds differ by a -CH₂- unit, this condition is satisfied.

### Step 4: Conclusion on the Assertion
Since both conditions for being a homologous series are met (same functional group and differing by -CH₂-), the assertion is true.

### Step 5: Understand the Reason
The reason states that a series of compounds with the same functional group but differing by a -CH₂- unit is called a homologous series. This is a correct definition of a homologous series.

### Step 6: Conclusion on the Reason
The reason is also true and correctly explains the assertion.

### Final Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct option is that both assertion and reason are true, and the reason is the correct explanation of the assertion.