The number of carbon atoms in the longest chain: 4
Parent alkane : Butane
Functional group: -CHO (al)
Assign the number: 1
Assign the number ‘1’ to carbon in the functional group
If the carbon chain of the compound contains a -CHO group then change the ending of the parent name, i.e. ‘e’ of the butane is replaced by ‘al’.
Parent suffix: Butanal
IUPAC name: Butanal