Hello Aspirant,

See if you are targeting for 99 percentile which is very good score in JEE-Main, then you need to cover all the topics because for such percentile you have to attempt the questions correctly as much as you can but still if you want the list of some important chapters then according to their weightage, chapters are enlisted below :

@Physics

• Rotational Motion
• Thermodynamics
• SHM
• Electrostatics
• Magnetism
• Optics
• Modern Physics

@Mathematics

• Complex Number
• Conic Section
• Circle
• Calculus
• Vector & 3 D
• Probability
• Trigonometric Equation
• Properties of Triangles
• Quadratic Equation
• Sequence and Series
• Permutations and combination

@Chemistry

• Chemical bonding
• Electrochemistry
• Coordination compound
• Salt analysis
• Ionic equilibrium
• Thermodynamics & thermochemistry
• Aldehydes and ketones
• Aromatic hydrocarbons
• GOC isomerism
• Liquid solutions
• Alkyl halides and aryl halides

For more details kindly check out the link given below:-

https://engineering.careers360.com/articles/most-important-chapters-of-jee-main

I hope this information helps you.

Good Luck!!