Hello

It's quite difficult to predict how many  questions in JEE mains comes from modern physics chapter as it keeps changing every year but if we go through past year trends then every year around question of 20 marks i.e 4 questions  are asked from the chapter modern physics

some other important topics or chapters are listed below based on their weightage in past year JEE mains examination :-

PHYSICS

Heat and Thermodynamics-12 marks

Optics - 12 marks

Current Electricity- 12 marks

Electrostatics- 12 marks

Magnetics- 8 marks

You can get JEE mains chapterwise weightage for each of physics chemistry and maths by visiting our page the link for the same is given below

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

Thank you