Isononanoic acid (also known as pelargonic acid) has a molecular formula of C9H18O2. It consists of a carbon chain with nine carbon atoms (C9) and a carboxyl group (COOH) at one end.
In isononanoic acid, there are no hydrogen atoms bonded directly to the carboxyl group. However, there are hydrogen atoms bonded to the carbon atoms in the carbon chain. Since there are nine carbon atoms in the chain, there would be 18 hydrogen atoms associated with those carbon atoms.
To give you a visual representation, the structure of isononanoic acid would look like this: