Assertion (A): In a homologous series of alcohols, the formula for the second member is `C_(2)H_(5)OH` and the third member is `C_(3)H_(7)OH`.
Reason (R): The difference between the molecular masses of the two consecutive members of a homologous series is 14u.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is true but R is false.
D. A is false and R is true.

Explanation

To solve the question, we need to analyze both the Assertion (A) and the Reason (R) given in the problem.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that in a homologous series of alcohols, the formula for the second member is \(C_2H_5OH\) and for the third member is \(C_3H_7OH\).
- The general formula for alcohols can be represented as \(C_nH_{2n+1}OH\).
- For \(n=2\), the formula becomes \(C_2H_{2(2)+1}OH = C_2H_5OH\) (which is correct).
- For \(n=3\), the formula becomes \(C_3H_{2(3)+1}OH = C_3H_7OH\) (which is also correct).
- Therefore, Assertion (A) is **true**.

2. **Understanding the Reason (R)**:
- The reason states that the difference between the molecular masses of two consecutive members of a homologous series is 14u.
- In a homologous series, each successive member differs by a \(CH_2\) unit.
- The molecular mass of \(CH_2\) is calculated as follows:
- Carbon (C) has an atomic mass of approximately 12u.
- Hydrogen (H) has an atomic mass of approximately 1u.
- Therefore, the molecular mass of \(CH_2\) = \(12u + 2(1u) = 14u\).
- This confirms that the difference in molecular masses between consecutive members is indeed 14u.
- Hence, Reason (R) is also **true**.

3. **Conclusion**:
- Since both Assertion (A) and Reason (R) are true, and the reason correctly explains the assertion, the correct answer is that both A and R are true, and R is the correct explanation of A.

### Final Answer:
Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.

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