Hello aspirant ,

I hope you are fine and doing well. As per your mentioned query , see jee mains is a national level of exam so you have to prepare the whole syllabus. As sometimes the topics that we thought that they are less important will come as a high weightage. So , try to not skip any concept and chapter. Here i will mention some important chapters that will helps you in your preparation.

Physics :

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

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

Mathematics :

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

So , these concepts are really fruitful.

For reference , visit the given link :

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

I hope this will be helpful for you.

Good luck !!