Padmam,

Check your init.ora, I bet you have the following parameter set in there: JOB_QUEUE_PROCESSES=4.

I'm 99% sure your processes 7 to 10 belongs to job queue processes. You could have found the answer by yourself if you have run the query I've provided in this thread:

SELECT s.sid, s.username, s.process, s.program, b.description background
FROM v$session s, v$bgprocess b
WHERE s.paddr = b.paddr(+);

Run it and see what is reported in the last column for those four processes.

HTH,