Which of the following represents a homologous series?

Question

Question

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AAI Junior Assistant (Fire Service) Official Paper (Held On: 15 Nov, 2022 Shift 2)

Answer 1

The correct answer is Option 1.

Key Points

A homologous series is a group of organic compounds with the same functional group and similar chemical properties.
The compounds in a homologous series differ by a constant unit, typically a -CH2- group.
In option 1, HCHO (formaldehyde), CH3CHO (acetaldehyde), and CH3CH2CHO (propionaldehyde) all belong to the aldehyde group, which is characterized by the presence of the -CHO functional group.
These compounds show a gradual change in physical properties such as boiling point and solubility, but their chemical properties remain consistent.

Additional Information

Functional Group:
- A functional group is a specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule.
- Examples include -OH in alcohols, -COOH in carboxylic acids, and -CHO in aldehydes.
Homologous Series Characteristics:
- Members of a homologous series have a general formula, like CnH2n+1CHO for aldehydes.
- They show a gradation in physical properties such as boiling and melting points.
- They exhibit similar chemical properties due to the presence of the same functional group.
Examples of Homologous Series:
- Alkanes (e.g., methane, ethane, propane)
- Alkenes (e.g., ethene, propene, butene)
- Carboxylic acids (e.g., formic acid, acetic acid, propionic acid)
Importance of Homologous Series:
- Simplifies the study of organic chemistry by grouping similar compounds together.
- Aids in predicting the properties and reactions of compounds within the same series.