Hi Bhargav Kakati

You have raised a good question and very basic too and basic concepts must be cleared.

For NEET, it is not necessary to pass in individual subjects. your overall score is going to be matter only. So, it wont matter from which subject you are scoring the marks, your rank will be decided only by the overall score you scored in exam. 

If a student clear the cut-off, he/she is eligible for admission to any college based on rank. He/she will be declared eligible if he get marks equal to or more than the cut-off irrespective of the subjects individual score.