Final answer:
An omega-6 fatty acid contains its first double bond at the sixth carbon from the omega end, with linoleic acid being an example.
Step-by-step explanation:
The fatty acid that contains its first double bond on the sixth omega carbon is an omega-6 fatty acid. To understand this, we look at where the double bond is located in relation to the omega end of the fatty acid chain, which is the end furthest from the carboxyl group. In the case of linoleic acid, which is a type of omega-6 fatty acid, the first double bond is found at the sixth carbon from the omega end. This contrasts with omega-3 fatty acids such as alpha-linolenic acid (ALA), where the first double bond is at the third carbon from the omega end. Omega-3 fatty acids are noted for their health benefits, including the potential to reduce the risk of heart disease and inflammation, and are found in foods like salmon and trout.