Your average qualification marks should be 50% in your +2 with subjects like Physics, Chemistry, Biology/Biotechnology and English as core subjects. Now you should have also individually passed all your subjects. Now if you haven't passed in Chemistry, you have to reappear in that paper. And if you want to write improvement exam for the rest of the subjects you may as well. Its important that before you join the Medical College, you should have passed your +2 with a minimum of 50% if you fall under General Category. You can appear for NEET.