Hey there!

There isn't any official weightage for chapters, however based on the previous years papers, a kind of approximate weightage is prepared for every chapter in the three sections i.e Phyics, Chemistry and Biology. To get a well explained information, and more details just go through this article- https://medicine.careers360.com/articles/neet-chapter-wise-weightage-and-important-topics

The best option for you will be to prepare for the neet in a well planned manner, for that i would recommend you to use NEET knockout plan of careers360.com , here's the link - https://learn.careers360.com/medical/neet/