Hi 

Most of the syllabus question from  NCERT books .

For biology , NCERT book is important .

Every year out of 90 questions , 85-88 questions from NCERT book only .

But out of 80 , 70-75 questions are direct questions .you can solve it .if you understand ncert completely .

Rest questions are confusing and tricky , though you read it very well you may mistake it ..

For physics NCERT is not enough to get full marks Only 3-5 example problem from NCERT not more than that .

In chemistry out of 20 , you can expect 15-17 from NCERT not more than that. .

To get more marks you can refer some other books like r.s agarwal and other auther like Pradeep's etc

Thanks