Write the formula of the functional group present in carboxylic acids.

28 What is the difference in the molecular mass of any two adjacent homologues? 28 By how many carbon atoms and hydrogen atoms do any two adjacent homologues differ? 29 Name the functional group present in CH₃ – C ≡ CH. 29 Name the functional groups present in the following compounds

(i) CH₃CHO (ii) CH₃CH₂COOH (iii) CH₃COCH₃ (iv) CH₃CH₂CH₂OH