Hello student yes you're eligible as per eligibility criteria Candidates who are appearing class 12 in 2020 and candidates who've passed in 2019 are eligible for BITSAT.

Eligibility - Candidates must passed or appearing class appearing class 12 in Physics chemistry and Mathematics with minimum 75 percent marks aggregate from a recognized board.

For more details refer to the link mentioned below - https://www.bitsadmission.com/Eligibility_Criteria.aspx#:~:text=The%20candidate%20should%20have%20obtained,in%2012th%20examination%2C%20with%20at

Feel free to comment if you've any doubt

Good luck