(9) and(10) tell about the positions and repetitions of the functional group or principal functional group (11) in a poly functional compound. It gives the information which carbon represents it or to which carbon that functional group is attached and how many times it is repeated. If it comes only once we need not write mono i.e., if no numerical prefix is present it is understood that the functional group is not repeated. Similarly, in the names of aliphatic compounds word root (5), primary suffix (8) and secondary suffix (11) are definitely present and all others may or may not be present. If there are more than one similar functional groups, ‘e’ letter of primary suffix may not be replaced.

If you find more than one functional group in the structure you select the principal functional group and write it as secondary suffix. All other functional groups become substituents.

A decreasing order of priority for choosing and naming a principal characteristic group. This should be written as secondary suffix.

(C) indicates that “C” of functional group is included in the main carbon chain.