There is no such Marks Distribution For JEE Mains but a trend can give you an Idea which are being prepared by Top Coaching Institutes of IIT-JEE.

IN 2019 JEE Mains trend shows that-

PHYSICS:- Physics, Heat & Thermodynamics, Optics, Current Electricity & Magnetism holds around 76 Marks Out of 120.

CHEMISTRY:- Transition Element, Coordinate Geometry , Periodicity, Thermodynamics, Gaseous State, Atomic Structure, Chemical Bonding, Solid State & Surface Chemistry, Chemistry in Everyday life, Biomolecules, Polymers, Aromatic Compounds holds around 80 Marks out of 120 .

MATHS:- vector ,3D, Statistics ,Probability, Matrices, Determinants, Complex Number, Quadratic Equation, Integral Calculus, Limits-Continuity & Differentiability  , and Coordinate Geometry Together makes 84 Marks of total 120 marks.

SO IF U EXCELLED IN THESE , LEAVING REST you can still score 66% Marks in Competitive Exam like Jee with >1Million Aspirants. With 198/300 U can get top 3 NITs (Technical Institutes) of Country for your B.Tech Degree & take Good Placements from Companies like Amazon, Google and Oracle with whopping 1M Rupees Per Annum as Salary.

GO & GRAB IT!