Hello Aspirant,No NCERT is a lonely not enough to get 90 percent as NCERT don't have much questions to practice for exam, Moreover you need some extra books specially in Physics for understanding chapter, you can't just read a chapter and can understand only using NCERT, and in Mathematics you also need some other books to practice questions.But if you studies from a good teacher who explains you the chapters easily and provides you questions from different sections to practice or you are studying in a good coaching where there is good teacher and they provides good study materials then you don't need extra books.