### Step-by-Step Solution:
#### 2.1 Define the term homologous series.
A homologous series is a series of compounds that have the same functional group and similar chemical properties, where each successive member in the series differs by a CH[tex]\(_2\)[/tex] group.
This implies that as you go from one compound to the next in the series, you simply add a CH[tex]\(_2\)[/tex] unit, which changes the molecular formula but retains the characteristic functional group and similar chemical reactivity.
#### 2.2 Write down the letter that represents an unsaturated hydrocarbon. Give a reason for your answer.
Upon examining all the compounds listed in the table, none of them indicate the presence of double or triple bonds, which are necessary in the structure for a compound to be classified as an unsaturated hydrocarbon. Unsaturated hydrocarbons have at least one carbon-to-carbon double bond (alkenes) or one carbon-to-carbon triple bond (alkynes).
Since there are no double or triple bonds in the given chemical formulas:
- Compound C: CC(C)O
- Compound D: [tex]\(CH_2(OH)CH_2C(CH_3)_2CH_2CH(F)CH_3\)[/tex]
- Compound E: Butanal
- Compound F: [tex]\(CH_3CH_2CHCH_2\)[/tex]
- Compound G: CCC(Br)C(C)C
- Compound H: Propanoic acid
None of these compounds fit the criteria for being unsaturated hydrocarbons.
Therefore, the letter that represents an unsaturated hydrocarbon does not exist among the given options, because none of the chemical formulas indicate a double or triple bond necessary for unsaturation.
#### 2.3 Is compound C a PRIMARY, SECONDARY or TERTIARY alcohol? Give a reason for your answer.
Compound C is represented by the structure: CC(C)O.
In this structure, the carbon atom attached to the hydroxyl group (OH) is also bonded to three other carbon atoms, making it a tertiary carbon. An alcohol is termed tertiary if the carbon carrying the OH group is connected to three other carbon atoms.
Thus, compound C is a tertiary alcohol. The reason is that the carbon atom to which the -OH group is attached is bonded to three other carbon atoms.
