An unsaturated fatty acid is .a. one in which carbon-carbon double bonds are present in the hydrocarbon chain. b. an odd number of subunits are present in the hydrocarbon chain. c. an even number of subunits are present in the hydrocarbon chain. d. carbon-carbon double bonds are not present in the hydrocarbon chain. e. not all of the carbons in the hydrocarbon chain are bonded to hydrogen atoms.

A. An unsaturated fatty acid is one in which carbon-carbon double bonds are present in the hydrocarbon chain.

Explanation:

In an unsaturated fatty acid there is atleast one or more carbon-carbon double bonds in its hydrocarbon chain. This means that an unsaturated fatty acid can be monounsaturated or polyunsaturated depending on the number of carbon-carbon double bonds in the hydrocarbon chain.

There is also reduction in the hydrogen atoms attached to the hydrocarbon chain. The maximum number of hydrogen bonded to the carbon in a saturated fatty acid is reduced in unsaturated ones. This structural differences affects the fatty acids in its low energy composition, susceptibility to lipid peroxidation and low melting point. Examples of unsaturated fatty acids are oleic acids, arachidonic acids, palmitoleic acids.

a. one in which carbon-carbon double bonds are present in the hydrocarbon chain.

Explanation:

Unsaturated fatty acids are long chain carboxylic acids with one or more double bonds between their carbon atoms.