Hello Amit, the eligibility criteria for NEET is a student must pass Physics, Chemistry and Biology/Biotechnology (inclusing practical test) or any other elective subject  with english.

For OBC category students the minimum perecntage in PCB should be 40%. You have more than 40% but it is mandatory for the candidate to pass in Physics, Chemistry and Biology.

You are eligible for NEET  only if you pass in chemistry exam and yes you can apply for NEET after getting pass marks in chemistry exam.

Don't lose hope. Be Confident.

All the best!