dear vanita, for eligibility purpose you should follow such points ....

• Candidates must have passed class 12 or equivalent examination (from any state or central board of school education)

• They should have secured at least 75% aggregate marks in the qualifying examination with Physics, Chemistry and Mathematics/Biology.

• Apart from the 75% aggregate marks, they should have scored 60% marks separately in each of the three subjects.

• Proficiency in English is another requirement for appearing in  exam.
  

• Only those candidates, who have cleared/passed class 12th or qualifying examination in the year 2017 or are appearing in 2018 are eligible for appearing in BITSAT 2018 .                                                                                                                                                                                                                Hope you got  your answer

Sorry to say you will not be eligible to get admission at BITS because you have to score 75% aggregate mark.

Eligibility criteria for BITSAT:-

• Candidates passed class 12 or equivalent examination (from any state/central board). However, they have to score 75% aggregate marks in Physics, Chemistry and Mathematics/Biology in the qualifying exam. Also, in each of the 3 subjects, they must also secure 60% marks separately.

• Aspiring candidates should also have proficiency in English to be able to appear in BITSAT 2018.

• Candidates who have appeared in class 12th in 2018 or 2017 would be considered eligible for BITSAT 2018.

All the very best and good luck.

No you are not eligible for BITSAT... Minimum 80% is required