Hey Gnana Teja,

Few of the best portals to write BARC online mock exams, The links are given below go through them,

1. https://www.google.co.in/amp/s/gradeup.co/tips-tricks-to-prepare-barc-2018-exam-i-78d68260-e9e7-11e6-93c2-5890d2210d79_amp

2. http://www.gate2016.info/barc-oces-dgfs-free-mock-tests/

3. https://toppersexam.com/ENGINEERING-ENTRANCE-EXAMS/BARC-OCES-DGFS-SO-EXAM/free-test_804.html