Which class of hydrocarbons consists of saturated compounds that contain only single covalent bonds between carbon atoms?

Introduction / Context:
This organic chemistry question asks about saturated hydrocarbons, which are compounds that contain only single bonds between carbon atoms and have the maximum number of hydrogen atoms possible. Hydrocarbons are divided into three main classes: alkanes, alkenes, and alkynes. Recognising which of these is saturated helps in predicting reactions and properties such as addition reactions and hydrogenation.

Given Data / Assumptions:
- The classes of hydrocarbons listed are alkenes, alkanes, and alkynes.
- Saturated means that all carbon carbon bonds are single bonds and the molecule contains as many hydrogen atoms as possible for its carbon skeleton.
- We assume standard definitions used in introductory organic chemistry.

Concept / Approach:
Alkanes are saturated hydrocarbons with only carbon carbon single bonds (C C) and general formula CnH2n+2 for acyclic molecules. Alkenes contain at least one carbon carbon double bond and are unsaturated. Alkynes contain at least one carbon carbon triple bond and are also unsaturated. Unsaturated hydrocarbons can add hydrogen across their multiple bonds in addition reactions, whereas saturated hydrocarbons cannot increase hydrogen content without breaking the skeleton. Therefore, among alkenes, alkanes, and alkynes, only alkanes are saturated hydrocarbons.

Step-by-Step Solution:
Step 1: Recall that alkanes have only carbon carbon single bonds and are considered saturated because no more hydrogen atoms can be added without breaking the carbon framework.
Step 2: Alkenes contain one or more carbon carbon double bonds (C=C). These double bonds can open up to add hydrogen, showing that alkenes are unsaturated.
Step 3: Alkynes contain one or more carbon carbon triple bonds (C≡C). These triple bonds can also be hydrogenated, indicating that alkynes are unsaturated.
Step 4: The question specifically asks for the class that represents saturated hydrocarbons, which must therefore be the alkanes.
Step 5: Options suggesting that all of the above are saturated are incorrect because alkenes and alkynes are unsaturated.

Verification / Alternative check:
Textbook tables of hydrocarbon series list alkanes as saturated hydrocarbons with general formula CnH2n+2, alkenes as unsaturated with CnH2n, and alkynes as unsaturated with CnH2n−2 for acyclic forms. Examples such as ethane (C2H6) are alkanes, ethene (C2H4) is an alkene, and ethyne (C2H2) is an alkyne. Only ethane among these has no multiple bonds and is fully saturated. This pattern confirms that only the alkane family is saturated.

Why Other Options Are Wrong:
- Alkene: Contains at least one double bond and can undergo addition reactions with hydrogen, so it is unsaturated.

Why Other Options Are Wrong (continued):
- Alkyne: Contains at least one triple bond and is also unsaturated, capable of adding hydrogen across the triple bond.
- All of the above: This is incorrect because only alkanes are saturated, while alkenes and alkynes are unsaturated hydrocarbons.

Common Pitfalls:
Students sometimes confuse the names alkane, alkene, and alkyne due to their similar spelling. A useful memory trick is that the simplest saturated hydrocarbon, methane, ends in ane, matching the family name alkane. Another source of confusion is thinking that a molecule is saturated if it contains any single bond, but the correct criterion is that it must have only single carbon carbon bonds and carry the maximum hydrogen content for its carbon skeleton.

Final Answer:
Alkane is the class of hydrocarbons that consists of saturated compounds with only single carbon carbon bonds.