Question

Arrange the following compounds in increasing order of their boiling points:

• A. (ii) < (i) < (iii)
• B. (i) < (ii) < (iii)
• C. (iii) < (i) < (ii)
• D. (iii) < (ii) < (i)

Hint:

Boiling point increases with chain length and molecular size due to stronger London dispersion forces.

Answer 1

The Correct Option is B

Step 1: Understanding boiling points. Boiling points are affected by molecular size and the type of intermolecular forces. The more carbon atoms and longer the chain, the higher the boiling point.

Step 2: Analysis of the compounds. - Compound (i) CH$_3$CH$_2$Br has a relatively small chain, resulting in a lower boiling point.
- Compound (ii) CH$_3$CH$_2$CH$_2$Br has a longer chain, leading to higher boiling point.
- Compound (iii) CH$_3$CH$_2$CH$_2$Br, with the largest size, has the highest boiling point.

Step 3: Conclusion. Thus, the correct order of boiling points is (i) < (ii) < (iii), corresponding to option (B).