>> I need know the impact in my oracle database 10g R2, if i change root/oracle passwords in my Oracle RAC enviromentChanging your root or Oracle OS user passwords will not effect RAC.
However, that is not true for the internal Oracle passwords. Depending on your configuation, some components of RAC many use embedded passwords (db_links, ertc.).
I would check with the DBA for this database to learn what components you are using.