i want to migrate the Oracle version from V7 to V8.
Can i do this with exp/imp. Is it possible to do this with
all V7 versions?
It is possible to do the migration. If it were me, I would want to get a new box to run my database, install Oracle, setup the database, migrate the data once while keeping the production system going and do testing. Then when I was satisfied that everything tested out fine, I would drop the new database and do a final cutover. This allows you to fix anything in the process before you are under any pressure to go live.
You may also have problems with the 9i import views if you go straight to 9i. But try it and if you get an error, there might be a metalink article on how to resolve it. I don't remember the specifics but I have on occassion had errors importing from one version to another.