Oracle Developer Question:

Answer #1
A data block size is specified for each ORACLE database when the database is
created. A database users and allocated free database space in ORACLE datablocks. Block size is specified in INIT.ORA file and cannt be changed latter.

Answer #2
The standard block size is specified by the initialization parameter DB_BLOCK_SIZE. In addition, you can specify of up to five nonstandard block sizes. The data block sizes should be a multiple of the operating system\\'s block size within the maximum limit to avoid unnecessary I/O. Oracle data blocks are the smallest units of storage that Oracle can use or allocate.