Name the functional group which always occurs in the middle of a carbon chain.

39 Write three common functional groups present in organic compounds. Give their symbols/formulae. 39 Name the functional groups present in the following compounds:

(i) CH₃COOH (ii)CH₃CH₂CH₂CHO (iii) C₂H₅OH (iv) CH₃COCH₂CH₃

39 Draw the structures for the following compounds:

(i) Ethanal (ii) Propanal (iii) Butanal (iv) Pentanal

40 What happens when carbon burns in air? Write the chemical equation of the reaction which takes place.