Majority of questions (about 95%) from Biology and Chemistry, will be from the NCERT. So read these books thoroughly.

For Physics, NCERT will clear your concepts, but the questions will not be directly from the NCERT. But they will have the same concepts. So, you need to practice questions from some other book.

All the best.

Dear Suchitra, while NTA hasnt released any syllabus for NEET UG as such, but going by previous trend, it has been advised to study NCERT books. Whether questions out of syllabus would be asked or not is within anyone's reach of imagination. So it is always good to be prepared. Having said that if you have recently completed your 10+2, it should be good enough because the basis of NEET UG is 10+2. Read NCERT, memorise Physics formulae and when in doubt, do not answer the qustion because you may lose a point due to negative marking.