Which functional group is present in the hydrocarbon chain of a detergent?

Which of the following does not belong to the same homologous series?

Why should we prefer vegetable oils over animal fats for cooking food? Give a balanced chemical equation for the reaction for hydrogenation of vegetable oils. Name the catalysts in this reaction.

Give a name to the reaction which takes place between ethanoic acid and ethanol in the presence of concentrated sulphuric acid. Write the chemical reaction and the name of the product obtained.

Ethane,with the molecular formula $C_{2}H_{6}$,has

Which of the following is not a straight chain hydrocarbon?