Hello aspirant,

Below I am mentioning the list all teh important chapters/topics for all the Subjects in JEE Mains and their Subject Wise weightage in decreasing order, that means the most important and the chapters carrying the most weightage is from top to bottom:

PHYSICS :

Modern Physics:- 20 marks

Heat and Thermodynamics :- 12 marks

Optics:- 12 marks

Current Electricity :- 12 marks

Electrostatics :- 12 marks

Magnetics :- 8 marks

Unit, Dimension and Vector:- 4 marks

Kinematics :- 4 marks

Laws of motion :- 4 marks

Work, Power and Energy :- 4 marks

Centre Of Mass, Impulse and Momentum :- 4 marks

Rotation :- 4 marks

Gravitation :- 4 marks

Simple Harmonic Motion :- 4 marks

Solids and Fluids :- 4 marks

Waves :- 4 marks

Electromagnetics Induction and AC :- 4 marks

CHEMISTRY :

Transition Elements and Coordination Chemistry  :-  12 marks

Periodic table and Representative Elements :- 12 marks

Thermodynamics And Gaseous State:- 8 marks

Atomic Structure:- 8 marks

Chemical Bonding:- 8 marks

Chemical And Ionic Equilibrium:- 8 marks

Solid State And Surface Chemistry :- 4 marks

Nuclear Chemistry And Environment:- 8 marks

Mole Concept :- 4 marks

Redox Reaction :- 4 marks

Electrochemistry :- 4 marks

Chemical Kinetics:- 4 marks

Solution and Colligative Properties :- 4 marks

General Organic Chemistry:- 4 marks

Stereochemistry:- 4 marks

Hydrocarbon :- 4 marks

Alkyl Halides :- 4 marks

Carboxylic Acid and their Derivatives:- 4 marks

Carbohydrates,amino acid and Polymers :- 4 marks

Aromatic Compounds :- 4 marks

MATHEMATICS:

Coordinate Geometry  :-  20 marks

Limits, Continuity and Differentiability :- 12 marks

Integral Calculus :- 12 marks

Complex numbers and Quadratic Equation :- 8 marks

Matrices and Determinants :- 8 marks

Statistics and Probability :- 8 marks

Vector Algebra :- 8 marks

Sets, Relation and Function:- 4 marks

Permutations and Combinations :- 4 marks

Binomial Theorem and Its Application:- 4 marks

Sequences and Series:- 4 marks

Trigonometry :- 4 marks

Mathematical Reasoning :- 4 marks

Differential Equation :- 4 marks

Statics and Dynamics :- 4 marks

Differential Calculus :-  4  marks

Further, to know more about the list of important chapters in all the subjects and to know more about the syllabus for JEE mains, you can follow the below mentioned link to know more  :-

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

I hope that this will help.

Good Afternoon

Hope you are doing great, as per your query the most important chapter in Jee main for physics are:

• Mechanics
• Oscillations And Waves
• Rotational Motion
• Electrostatics
• Atoms And Nuclei
• Current Electricity
• Magnetic effect of Current and Magnetism

In Chemistry:

• Organic Compounds Containing Oxygen
• Equilibrium
• Chemical Kinetics
• Transition Elements (d and f block)
• s-block Elements
• Chemical Bonding And Molecular Structure
• Some Basic Principles Of Organic Chemistry
• p-block Elements
• Coordination Compounds
• Chemical Thermodynamics

And in Maths:

• Integration
• Differentiation
• Probability
• Three Dimensional Geometry
• Trigonometry
• Vector Algebra
• Conic Sections
• Straight Lines
• Sets, Relations and Functions
• Matrices And Determinants

And for full Syllabus for JEE Main you can visit this link below

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

Hope you found this answer helpful
All the Best