Hi Pando and the rest,
I coalesced the tablespace and run the query again and I got the same results
SQL> SELECT a.table_name, a.next_extent, a.tablespace_name
FROM all_tables a,
( SELECT tablespace_name, max(bytes) as big_chunk
FROM dba_free_space
GROUP BY tablespace_name ) f
WHERE f.tablespace_name = a.tablespace_name
AND a.next_extent > f.big_chunk

SQL> /

TABLE_NAME NEXT_EXTENT TABLESPACE_NAME
----------- ---------- ------- -------
EMPLOYEE 460800000 ORANGE


What do you think is the next thing to do?