Here are the important topics with its weightage given below:

The important topics to study:

Physics

Mechanics- 30%

Heat & Thermodynamics -7%

Electrostatics & Current Electricity- 17%

Magnetics & Electro Magnetic Induction- 13%

Optics & Waves- 3%

Modern Physics- 10%

Simple Harmonic Motion, Waves & Elasticity- 7%

Semi-Conductor Devices, Electromagnetic Waves and Principles of Communication- 13%

Chemistry

Organic Chemistry- 30%

Inorganic Chemistry- 30%

Physical Chemistry- 40%

Mathematics

Co-Ordinate Geometry- 17%

Calculus- 27%

Algebra- 27%

Vector/3-D Geometry- 10%

Trigonometry- 6%

Sets & Relations, Mathematical Reasoning, Statistics- 13%

You can also refer the below given article for the further information

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

Good Luck!

Hey.

Here is a list of important topics for JEE mains and their respective weightages.

Maths-

Percentage Co-Ordinate Geometry 17%

Calculus 27%

Algebra 27%

Vector/3-D Geometry 10%

Trigonometry 6%

Sets Relations, Mathematical Reasoning, Statistics 13%

Physics-

Mechanics 30%

Heat Thermodynamics 7%

Electrostatics Current Electricity 17%

Magnetics Electro Magnetic Induction 13%

Optics Waves 3%

Modern Physics 10%

Simple Harmonic Motion, Waves Elasticity 7%

Semi-Conductor Devices, Electromagnetic Waves and Principles of Communication 13%

Inorganic Chemistry- Classification of Elements and Periodicity in Properties, General Principles and Process of Isolation of Metals, Hydrogen, s - Block Elements (Alkali and Alkaline Earth Metals), Co-ordination Compounds, Environmental Chemistry to name few.  

Organic Chemistry- Purification and Characterisation of Organic Compounds, Some Basic Principles of Organic Chemistry, Hydrocarbons,Organic Compounds Containing Oxygen, Organic Compounds Containing Nitrogen, Bio Moleculesetc.  

Physical Chemistry- Some Basic concepts in Chemistry,States of Matter, Atomic Structure, Chemical Bonding and Molecular Structure,Chemical Thermodynamics, Equilibrium, Surface Chemistry,Chemical Kinetics and Redox Reactions and Electrochemistry.  

You can use the link below for more details.

https://www.google.co.in/amp/s/engineering.careers360.com/articles/jee-main-syllabus-weightage/amp