The word is that the syllabus might be reduced for NEET and JEE Mains owing to the reduced Academic year due to the pandemic. While the topics have not been declared officially yet, MHRD did announce that there will be a live interaction that will happen on December the 10th where in students, parents, teachers can ask the HRD Minister questions by tagging #EducationMinisterGoesLive. Until then, this question will be answered with the information that is relevant for now. You can check the entire syllabus at: https://engineering.careers360.com/articles/jee-main-syllabus and to give you the weightage of these chapters,  in Physics, Modern Physics take the top slot with 5 questions. Heat and Thermodynamics, Optics, Current Electricity, Elcetrostatics get 3 questions each. Magnetic has 2 questions and the rest get 1 question each. In Chemistry, Transition Elements and Coordination Chemistry, Periodic Table and Representative elements take 3 questions slot. Thermodynamics and Gaseous state, Atomic structure, Chemical Bonding, Chemical and Iconic Equilibrium, Solid State and Surface Chemistry and Nuclear Chemistry and Environment get 2 questions slot each and the remaining get 1 question each.In Mathematics, Co-ordinate Geometry gets 5 questions. Limits, Continuity and Differentiability, Integral Calculus get 3 questions slot each. The rest get 2 and 1 questions slot. For complete breakdown, please read our article: https://engineering.careers360.com/articles/jee-main-syllabus-weightage .