Dear Sayoni

While writing the trivial names of substituents, the prefixes iso- and neo- are considered to be the part of the fundamental naming or IUPAC naming of alkyl group. The prefixes such as sec- and tert- are not considered to be the part of the fundamental name as they are not allowed by the IUPAC naming. The use of iso, neo and related common prefixes for naming alkyl groups is allowed by the IUPAC nomenclature as long as these are not further substituted.

Example:

Regards

Topperlearning Team.