Use the following (modify as necessary):

declare
cursor_name integer;
rows_processed integer;
cursor c1 is select table_name from user_tables where tablespace_name='TABLESPACE_NAME_IN_CAPITALS';
stmt varchar2(1024);
begin
cursor_name := dbms_sql.open_cursor;
for mc1 in c1 loop
stmt := 'select 9 from '||mc1.table_name||' where rownum < 2';
dbms_sql.parse(cursor_name,stmt,dbms_sql.native);
rows_processed := dbms_sql.execute_and_fetch(cursor_name);
if rows_processed = 0 then
dbms_output.put_line(mc1.table_name||' has '||to_char(rows_processed)||' rows');
end if;
end loop;
dbms_sql.close_cursor(cursor_name);
end;


-amar