Generally speaking, you can convert any archive to another, provided you have all the pieces if the archive is split. However, it does not make sense to convert individual pieces so this conversion is not possible.
Convert Split file or Compressed file from a multi-volume archive (part 25) to Compressed file from a multi-volume archive (part 5).
We found 2 software records in the database related to .025 to .005 file format conversion.
Microsoft Windows software - convert 025 to 005 on Windows
Popular open source file archiver with a high compression ratio
Convert from 025 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned 025 to 005. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
One of the oldest and most popular shareware file archiver and data compression utility