ps -ef | grep oracle

On Unix the command is ps -aef | grep -i pmon

A B-Tree index stores the index value and the physical rowid of the row. The index values are arranged in the form of leaves. A B-Tree index is used most when the cardinality is high. A Bitmap index ...

For example suppose we have using many distinct value for particular column in that time using b-tree index.

Bitmap indexes which is used low cardinaties values .
For example suppose we have using gender or flag column in that time using bitmap index .