i) The number of carbon atoms in the longest chain is two and two aldehyde groups are present. Thus, IUPAC name of the above compound is Ethane-1,2-dial.

ii) Here, two aldehyde groups are attached to the benzene ring. Two –CHO groups are attached the carbon atom at position 1 and 4. Thus, IUPAC name of the above compound is Benzene-1, 4-dicarbaldehyde.

iii) Here, a bromine atom is attached at the 3^rd position with respect to the aldehyde group on the benzene ring. Thus, IUPAC name of the above compound is 3-Bromobenzaldehyde.