I am really sorry to tell you that you are not eligible for the BITSAT examination. Since as per the BITSAT eligibility criteria, the aspirants must have an aggregate of 75% and above in PCM and also 60% marks and above in each of these subjects that is Physics, Chemistry and Mathematics.

Refer the site below for knowing more about the same..

https://engineering.careers360.com/articles/bitsat-eligibility-criteria

Best wishes. Thank you.