on which chapters of bio and chem i need to concentrate to score 400 in neet 2020, pls intimate the chapters
There is no such rules of topic wise weightage or chapter wise, but if you follow the recent trend or if you consider previous few year's question then you can see that these three topics are mostly asked in NEET under Biology.
Genetics and Evolution-18%
Diversity of Living Organisms-14%
For chemistry i would suggest you to clear all the concepts of Organic chemistry.
Please follow NCERT for Inorganic.
All the best!!