During the nomenclature of branced alkanes, generally some prefixes are used such as n, iso, neo and n (normal) ect.

Condition for following prefixes:-

1)  n (normal) prefix: when carbon form a continous  or linear chain.

2) iso prefix :when the second carbon of the branced chain alkane carries one methyl group.

3) neo prefix: when quaternary carbon at the end of the chain.

similary if we can do nomenclature of the compound, position number 5th carbon  shows iso prefix