Hello aspirant

Hope you are doing well as every chapter have its own importance but there are some chapters which have high weightage and these chapters can increase your marks so here is the list of some chapters

For biology

Human Physiology , Diversity in living world, Structural organisation's in plant and animal( Morphology and anatomy of plants ), cell structure and function , plant physiology, reproduction , genetic and evolution, ecology and environment

For physics

Mechanics ,work power and energy, gravitation rotation, oscillation and waves , alternating current, electrostatic, atoms and nuclei

For chemistry

Chemical bonding ,p block iupac nomenclature ,equilibrium,  d and f block , coordination Compounds, polymers

Below is the link.for sample papers for neet

https://medicine.careers360.com/articles/neet-sample-paper

Good luck

Hope it helps .