Yes you can. I am a example.i was very weak in physics.Now I get 62 marks in jee advance 2018 in physics.You can also do it but do not forget other subjects.Try your best.you can crack iit.but practice is required.Devolopment of your concepts is better than question solving.Solve questions but not many more.IIT never repeats questions so you must hard work.If you are 12 passed then you will be face a little difficulty.