are ncert books of class 9 and 10 enough for the preparation of KVPY in class 11? also give me some tips to study so that i can crack KVPY ?

No. you need to have a practice of advanced level questions involving multilateral concepts of the subjects. It’d be better if you start solving questions from the JEE Mains question bank or some other question banks involving questions based on the the same concepts. For concepts, go for a subjective reference material. And later on, step up for competetive questions.
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