Question

The alcohols, methanol, ethanol, propanol, butanol, etc. form a homologous series. This means they have:
A. Similar chemical properties, but gradually changing physical properties.
B. Similar physical properties, but gradually changing chemical properties.
C. The same molecular formula, but different physical properties.
D. Similar physical properties and the same structural formula.

Answer 1

Hint: A group of atoms attached to a molecule that impart similar chemical and physical properties to compounds is known as a functional group. A sequence of organic compounds that have the same functional group is known as homologous series. The members of the homologous series can be branched or unbranched.

Complete step by step answer:
The compounds in the homologous series have the same functional group. Thus, all the compounds in the homologous series have similar chemical properties.
The physical properties of the compounds in the homologous series vary depending on the structures and the substituent groups attached.
The general formula of the compounds in the homologous series is same but molecular formula of the compounds of the homologous series cannot be same and differs by $\text{C}{\text{H}}_2$ for each compound and thus, their structural formulas also cannot be same.
Thus, the compounds of the homologous series have similar chemical properties, but gradually changing physical properties.
The alcohols, methanol, ethanol, propanol, butanol have hydroxyl $\left(-\text{OH}\right)$ functional group.
Thus, the alcohols, methanol, ethanol, propanol, butanol, etc. form a homologous series. This means they have similar chemical properties, but gradually changing physical properties.

So, the correct answer is “Option A”.

Note:
The physical properties of the compounds in the homologous series vary gradually because of the sizes of the molecules. The physical properties such as boiling point, density, etc. vary because of the size of the molecules. The chemical properties of these molecules are similar because they have the same functional group attached.