Question

The correct decreasing order of priority of the functional groups of organic compounds in the IUPAC system of nomenclature is
(A) $-COOH,-S{{O}_{3}}H,-CON{{H}_{2}},-CHO$
(B) $-S{{O}_{3}}H,-COOH,-CON{{H}_{2}},-CHO$
(C) $-CHO,-COOH,-S{{O}_{3}}H,-CON{{H}_{2}}$
(D) $-CON{{H}_{2}},-CHO,-S{{O}_{3}}H,-COOH$

Answer 1

Hint: A functional group is defined as, is an atom or group of atoms bonded together in a unique manner which is usually the site of chemical activity in an organic molecule. Compounds having the same functional group undergo similar reactions.

Complete answer:
The functional group present in the molecule is identified which determines the choice of appropriate suffix.
The longest chain of carbon atoms containing the functional group is numbered in such a way that the functional group is attached to the carbon atom possessing the lowest possible number in the chain.
In the case of polyfunctional compounds, one of the functional groups chosen as the principal functional group, and the compounds are then named on that basis. The remaining functional groups, which are subordinate functional groups, are named as substituents using the appropriate prefixes.
The choice of the principal functional group is made based on an order of preference.
The order of decreasing priority for some functional groups is:
$-COOH>-S{{O}_{3}}H>-COOR,>-COCl>-CON{{H}_{3}}>-CN>-CHO>-C=O>OH>-N{{H}_{3}}>-C=C->-C\equiv C-$ Hence, The correct decreasing order of priority of the functional groups of organic compounds in the IUPAC system of nomenclature is,
$-COOH,-S{{O}_{3}}H,-CON{{H}_{2}},-CHO$

The correct answer is option A.

Note:
If more than one functional group of the same type is present, their number is indicated by adding di, tri, etc. before the class suffix. In such cases, the full name of the parent alkane is written before the class suffix.