State the general formula of the homologous series to which propanoic acid belongs

The general formula for the homologous series to which propanoic acid belongs, which is the carboxylic acid series, is CnH2n+1COOH.

Here's how we get to that:

1. Identify the series: Propanoic acid is a carboxylic acid, so it belongs to the carboxylic acid series.

2. Understand the structure: Carboxylic acids have a carbon (C), hydrogen (H), and oxygen (O) atoms. They also have a functional group COOH.

3. Formulate the general formula: In the general formula CnH2n+1COOH, 'n' represents the number of carbon atoms. The '2n+1' represents the number of hydrogen atoms, which is always double the number of carbon atoms plus one. The 'COOH' is the carboxylic acid functional group.

So, for any member of the carboxylic acid series, you can determine its molecular formula by replacing 'n' with the number of carbon atoms in that molecule.