One of the following burns without producing a flame. This is:

42 One of the following molecular formula can represent two organic compounds having different functional groups. This molecular formula is : 43 The number of carbon atoms present in the molecule of fifth member of the homologous series of alkynes is: 45 The functional group which always occurs in the middle of a carbon chain is : 46 The molecular formulae of some organic compounds are given below. Which of these compounds contains an aldehyde group?