The functional group which always occurs in the middle of a carbon chain is :

43 The number of carbon atoms present in the molecule of fifth member of the homologous series of alkynes is: 44 One of the following burns without producing a flame. This is: 46 The molecular formulae of some organic compounds are given below. Which of these compounds contains an aldehyde group? 47 The organic compounds which are isomeric with one another are: