Question

Among the following compounds $\mathrm{A}$ and $\mathrm{B}$ with the molecular formula ${\mathrm{C}}_9{\mathrm{H}}_{18}{\mathrm{O}}_3$, $\mathrm{A}$ has higher boiling point than $\mathrm{B}$. The possible structures of $\mathrm{A}$ and $\mathrm{B}$ are:

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The correct option is B

Explanation for correct option:

(B)

1. Here, the boiling point of $\mathrm{A}$ is higher than that of $\mathrm{B}$.
2. Compound $\mathrm{A}$ is alcohol with $\mathrm{H}$-bonding , which makes the boiling point of the compound is higher.
3. $\mathrm{H}$-bonding is the interaction between hydrogen and the most electronegative elements which makes the compounds having $\mathrm{H}$-bonding have high boiling point then their other counterparts.
4. Compound $\mathrm{B}$ is ether, it doesn't show $\mathrm{H}$-bonding hence it has lower boiling point than alcohol

Explanation for incorrect options:

(A)

1. Here, the boiling point of $\mathrm{B}$ is higher than that of $\mathrm{A}$.
2. Compound $\mathrm{B}$ is alcohol with more $\mathrm{H}-\mathrm{bonding}$, which makes the boiling point of these molecules higher.
3. Compound $\mathrm{A}$ is ether, it doesn't show $\mathrm{H}-\mathrm{bonding}$ thus the boiling point is lower.

(C)

• Here, the boiling point of $\mathrm{B}$ is higher than that of $\mathrm{A}$.
• Compound $\mathrm{B}$ is alcohol with more $\mathrm{H}-\mathrm{bonding}$, which makes the boiling point of these molecules higher.
• Compound $\mathrm{A}$ is ether, it doesn't show $\mathrm{H}-\mathrm{bonding}$ thus the boiling point is lower.

(D)

• Here, the boiling point of $\mathrm{B}$ is higher than that of $\mathrm{A}$.
• Compound $\mathrm{B}$ is alcohol with more number of hydroxyl groups hence, more $\mathrm{H}-\mathrm{bonding}$, which makes the boiling point of these molecules higher.
• Compound $\mathrm{A}$ is also alcohol with fewer hydroxyl groups hence less $\mathrm{H}-\mathrm{bonding}$ thus the boiling point is lower.

Hence, option B is correct.