Question

name the compound and what is difference between homologous series and functional group

Answer 1

The name of the compound is Prop-2en-1-al

Answer 2

A homologous series is a group of organic compounds which belong to the same family (i.e. possess same functional group) and show similar chemical properties. The members of this series are called homologue and differ from each other by the number of CH2 units in the main carbon chain. Following are the characteristics of a homologous series

All homologues of a series have the same general formula e.g., all alkanes have the general formula CnH2 n + 2, alkyl halides have the general formula CnH(2n+1)X
Each consecutive member differs from the next by one carbon atom and two hydrogen atoms (-CH2 group).
The difference in the molecular mass between two consecutive homologues is 14 amu.
The physical properties of homologues show a regular gradation.
Homologues of a series have similar chemical properties.

Example propane and pentane are the homologues of butane.

Please note that homologous group is a term that is not defined and used in Chemistry. However, the term functional group is more commonly encountered. Functional group is an atom or a group of atom, which is binded to carbon chain and it defines the chemical property of the organic compound. For example, OH is an alcohol, CHO is an aldehyde etc.