Concept:General chemical formulas can identify entire homologous series based on their degree of unsaturation.
Solution:- The formula for an open-chain, fully saturated alkane is \( C_nH_{2n+2} \).
- The general formula \( C_nH_{2n}O \) is missing two hydrogen atoms compared to a saturated alkane, which indicates exactly one degree of unsaturation (one double bond or one ring).
- Since the oxygen is present, this double bond is between carbon and oxygen (\( C=O \)).
- This characteristic matches the structure of open-chain aliphatic Aldehydes and Ketones.
Why other options are incorrect:Ethers are fully saturated and have the formula \( C_nH_{2n+2}O \). Carboxylic acids have two oxygen atoms, so their formula is \( C_nH_{2n}O_2 \). Carbolic acid is phenol, an aromatic ring with a vast hydrogen deficiency.
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