Hi reader ,

for JEE each chapter is very important and you should focus on all of them but there are certain chapters in each subject which have higher weightage:

In PHYSICS following chapters are important:

1)Modern Physics

2)Heat & Thermodynamics

3)Electrodynamics (it includes electrostats , capacitors , current electricity , magnetism , emi , ac)

4)Optics (both ray and wave)

In MATHEMATICS following chapters are important:

1)Integral Calculus

2)Matrix & Determinants

3)Co-ordinate Geometry (3-D)

4)Probability

In CHEMISTRY following chapters are important:

1)Biomolecules

2)Polymers

3)Carbonyl Compounds

4) Thermodynamics and Thermochemistry

5)Chemical Bonding, Periodic Table

6)P block , Dand F block

i hope this helps

for more information you can refer

https://engineering.careers360.com/articles/jee-main-syllabus-weightage

thank you