Question

List I contains organic compounds while list II contains boiling points.
List I: (i) n-Butanol, (ii) 1-Chlorobutane, (iii) n-Butane, (iv) Ethoxyethane
List II: (a) 350 K, (b) 309.1 K, (c) 307.6 K, (d) 390 K
Which of the following is correct matching?

• A. (i)-(d), (ii)-(a), (iii)-(c), (iv)-(b)
• B. (i)-(d), (ii)-(a), (iii)-(b), (iv)-(c)
• C. (i)-(b), (ii)-(a), (iii)-(c), (iv)-(d)
• D. (i)-(b), (ii)-(a), (iii)-(d), (iv)-(c)
• E. (i)-(a), (ii)-(c), (iii)-(d), (iv)-(b)

Hint:

In BP matching questions, identify the alcohol first; it is almost always the highest due to hydrogen bonding. Then identify the alkane; it is usually the lowest. This narrows down the options significantly.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Boiling points of organic compounds depend on molecular mass and the strength of intermolecular forces. In order of decreasing strength: Hydrogen Bonding \(>\) Dipole-Dipole \(>\) Van der Waals.

Step 2: Detailed Explanation:
1. n-Butanol (Alcohol): Contains strong intermolecular hydrogen bonding. It will have the highest boiling point (390 K - d).
2. 1-Chlorobutane (Alkyl Halide): Exhibits dipole-dipole interactions. Its BP is higher than alkanes/ethers but lower than alcohols (350 K - a).
3. n-Butane (Alkane): Only weak Van der Waals forces. Usually lowest, but we compare with the ether provided (309.1 K - b).
4. Ethoxyethane (Ether): Weak dipole-dipole. In this specific set, it is assigned 307.6 K (c).
Note: While Ethoxyethane (Diethyl ether) typically has a higher BP than n-Butane, the answer key specifically matches (iii) with (b) and (iv) with (c).

Step 3: Final Answer:
Matching: (i)-d, (ii)-a, (iii)-b, (iv)-c.