Homologous series:

A homologous series is a group of organic compounds that have the same functional group and a similar chemical structure. The compounds in a homologous series can be represented by a general formula and exhibit similar physical and chemical properties. Each member of the series differs from the previous one by a specific unit, such as a CH2 group.

Alkanes:

Alkanes are a class of hydrocarbons that contain only single covalent bonds between carbon atoms. They are also known as saturated hydrocarbons because each carbon atom is bonded to the maximum number of hydrogen atoms. The general formula for alkanes is CnH2n+2, where n represents the number of carbon atoms in the molecule.

C3H8:

C3H8 is the chemical formula for propane, which consists of three carbon atoms and eight hydrogen atoms. Propane is an alkane because it contains only single covalent bonds and follows the general formula for alkanes (CnH2n+2). Therefore, the correct answer to the question is option 'B' - Alkanes.

Explanation:

To determine the correct answer, we need to analyze the chemical structure of C3H8 and compare it to the general formula of each homologous series.

- Alkynes: Alkynes are hydrocarbons that contain at least one triple bond between carbon atoms. Since C3H8 does not have a triple bond, it does not belong to the alkynes series.

- Alkenes: Alkenes are hydrocarbons that contain at least one double bond between carbon atoms. Since C3H8 does not have a double bond, it does not belong to the alkenes series.

- Cycloalkanes: Cycloalkanes are hydrocarbons that form a closed ring structure with single covalent bonds. C3H8 does not have a ring structure, so it does not belong to the cycloalkanes series.

- Alkanes: Alkanes are hydrocarbons that contain only single covalent bonds. C3H8 fits this description as it consists of carbon atoms bonded to each other by single bonds and is saturated with hydrogen atoms. Therefore, C3H8 belongs to the homologous series of alkanes.

In conclusion, C3H8 belongs to the homologous series of alkanes because it follows the general formula for alkanes (CnH2n+2) and contains only single covalent bonds.