Jyoti, So to be eligible for NEET, you should have completed your 12th, passed in all subjects and secure a minimum aggregate of 50% in Physics, Chemistry and Biology. It is 50% for General Category, 45% for PWD and 40% for OBC,SC,ST. Now if you belong to OBC Category, the Category you belong to should be also listed in the Central OBC list. Or else you will be considered as General Category and so you have to secure a minimum aggregate of 50% in Physics, Chemistry and Biology. This 50% is inclusive of the Theory and Practical marks scored in Physics, Chemistry and Biology collectively. You needn't score 50% in Physics, 50% in Chemistry and 50% in Biology separately. You need an aggregate of 50% or 40% depending on your Category as an aggregate in Physics, Chemistry and Biology. And along with Physics, Chemistry and Biology, you should also have studied English as one of the core subjects in your 12th. So even if you have failed in Physics in your first attempt and then appeared for Betterment exams, then passed and secured the minimum aggregate of 40-50% against your Category, you are eligible for NEET.
First of all, in neet there is criteria of percentile nowadays. So no one can be judged on behalf of fail or pass. Now come to part of physics, so being a medical aspirant you should have good grip over physics in order to improve your rank. This will help you alot to get good rank. I suggest you should not avoid it.