Question

Which of the following has the lowest solubility in water ?
A. $C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}OH$
B. $C{{H}_{3}}-CC{{H}_{3}}HC{{H}_{2}}OH$
C. $HO{{H}_{2}}C-C{{H}_{2}}OH$
D. ${{C}_{6}}{{H}_{5}}C{{H}_{2}}C{{H}_{2}}OH$

Answer 1

Hint: In this question, we have to answer the option which has the lowest solubility. For this, we must have the knowledge of how solubility differs in these types of compounds.

Complete Step by Step Solution:
As we see in the question, all the given chemicals are alcohols.
Alcohols are polar compounds due to the difference in the electronegativities of carbon and oxygen. As a result, alcohols make bonds with each other and with polar compounds with the help of hydrogen bonding and dipole- dipole interactions.

Alcohols can be primary, secondary or tertiary depending on the carbon chain and the position of the hydroxyl group of alcohol and water molecules forming hydrogen bonding. Since the interactions are strong, they are easily soluble in water. But when we move towards the higher alcohol, the solubility goes on decreasing because alcohols act like alkanes. The large hydrocarbon part is hydrophobic and hence there are low chances of solubility.

From the given above options, the largest alcohol is ${{C}_{6}}{{H}_{5}}C{{H}_{2}}C{{H}_{2}}OH$and thus have lowest solubility in water.
Thus, Option (D) is correct.

Note: Students must have the knowledge of the compounds to answer these types of questions. Alcohols also have high boiling points due to their polar nature. The hydroxyl group of two alcohol molecules form intermolecular hydrogen bonds with each other. So the boiling point goes on increasing with the increase in the number of carbon atoms. So alcohol has a high boiling point.