Explanation
Not A: Both indexes are created fine.
B: The invisible index ORD_CUSTOMERS_IX1 and the bitmap index are both updated by DML operations on the Orders table.
F: Since ORD_CUSTOMERS_IX1 is invisible only ORD_CUSTOMERS_IX2 is used by the query optimizer.

B:
*A PDB would have its SYSTEM, SYSAUX, TEMP tablespaces.It can also contains other user created tablespaces in it.
*There is one default temporary tablespace for the entire CDB. However, you can create additional temporary tablespaces in individual PDBs.
D:
*There is a single redo log and a single control file for an entire CDB
*A log switch is the point at which the database stops writing to one redo log file and begins writing to another. Normally, a log switch occurs when the current redo log file is completely filled and writing must continue to the next redo log file.
G: instance recovery The automatic application of redo log records to uncommitted data blocks when an database instance is restarted after a failure.
Incorrect: Not A:
*There is one set of background processes shared by the root and all PDBs. -
*High consolidation density. The many pluggable databases in a single container database share its memory and background processes, letting you operate many more pluggable databases on a particular platform than you can single databases that use the old architecture.
Not C: There is a separate SYSAUX tablespace for the root and for each PDB.
Not F: There is a separate SYSTEM tablespace for the root and for each PDB. -

Explanation
5.2 Overview of the Automatic Workload Repository
The Automatic Workload Repository (AWR) collects, processes, and maintains performance statistics for problem detection and self-tuning purposes. This data is both in memory and stored in the database. The gathered data can be displayed in both reports and views.
The statistics collected and processed by AWR include:
References:
http://docs.oracle.com/cd/B28359_01/server.111/b28274/autostat.htm#PFGRF02601

B:The target database must be mounted with a current control file, that is, the control file cannot be a backup or have been re-created.
D: You must OPEN RESETLOGS after running FLASHBACK DATABASE. If datafiles are not flashed back because they are offline, then the RESETLOGS may fail with an error.
Note:
*RMAN uses flashback logs to undo changes to a point before the target time or SCN, and
then uses archived redo logs to recover the database forward to make it consistent. RMAN
automatically restores from backup any archived logs that are needed.
*SCN: System Change Number
*FLASHBACK DATABASE to One Hour Ago: Example
The following command flashes the database by 1/24 of a day, or one hour:
RMAN> FLASHBACK DATABASE TO TIMESTAMP (SYSDATE-1/24);