97. What is User Account in Oracle database?
A user account is not a physical structure in database but it is having important relationship to the objects in the database and will be having certain privileges.

98. How will you enforce security using stored procedures?
Don't grant user access directly to tables within the application.
Instead grant the ability to access the procedures that access the tables.
When procedure executed it will execute the privilege of procedures owner. Users cannot access tables except via the procedure.

99. What are the dictionary tables used to monitor a database space?
DBA_FREE_SPACE
DBA_SEGMENTS
DBA_DATA_FILES