Question

IUPAC name of $C{H}_{3}COC{H}_3$ is
A) Acetone
B) $2$ -propanone
C) Dimethyl ketone
D) Propanal

Answer 1

Hint: The nomenclature of the organic structure is based on the type of residues or the functional groups which are involved in the formation of the given molecule. The bonded forms of the residues are responsible for the chemical nature of the molecules as well.

Complete step by step answer
The IUPAC nomenclature of any given organic molecule is defined by the main chain structure of the molecule and the associated structure. The associated bonding of the molecule includes different types of functional groups which form the branching from the main chain structure. The nomenclature at first defines the number of carbon residues in the main chain structure based on which the first set of nomenclature is defined. The next choice of nomenclature is defined by the type of functional group or the association of the branched-chain structure. The branching is part of the nomenclature and it is defined based on the carbon number of the main chain structure with which the branching is associated. There are specific prefixes and suffixes which are used for naming the structure of the organic molecule.
The IUPAC nomenclature of the specific molecule $C{H}_{3}COC{H}_3$ is formed with the central carbon to form the ketone as a part of the carbon structure. The ketone is the functional group which is present as part of the $2nd$ carbon in the three-carbon chain. This is why the main chain is a propane with the functional group ketone $\left(C=O\right)$ as a part of the main structure. The ketone is formed from the $2nd$ carbon molecule. Therefore, the IUPAC nomenclature for the giving molecule is B. $2$ -propanone.

Hence, option B is correct.

Note
The structure of the organic molecule depends on branching as well as the main chain form. It is important to know the direction from which the carbon number needs to be counted so that the carbon number with which the branching is present can be defined properly.