Question

Which of the following group should be written as prefix substituent always in IUPAC nomenclature,
(1) -NO2
(2) -COOH
| (3) -CONH2
(4) -NH2​

Answer 1

Answer: - NO2

Explanation: Since the order of the functional group is as follow ;

-COOH > - COOR > - SO3H  > -COX > - CONH2 > - CHO > - CN > -NC > KETONE > OH > - NH2 > - C = C -  > ALKYNE >  -OR > -NO2 > -X > - R ( -CH3 or - C2H5)

from this order substituent shoukd be  -NO2.