what are the important chapters for neet?

Dear first of all you have to do preparation from whole NCERT after that you focus on the important chapters. In exam any of the question can come so thoroughly read the whole NCERT book of class 11 and 12 as well...
Physics: Mechanics is the most important topic. 12-13 questions were asked on it last time.
Chemistry: Organic Chemistry dominates the chemistry question paper. 14-15 questions were from topics related to it.
Biology: There was a more uniform distribution of questions in Biology. There was no single unit or topic from which more than 6 questions were asked. Hence it would be wrong to deem any one single chapter most important as all are important.