As both are important but comparatively 12th carries more weightage as you can check the subject wise weightage below as well-

Chemistry - General Organic Chemistry 9% Alcohol Phenol Ether 7% Redox reactions 6% Chemical Bonding 5% Coordination Compound 5% P-Block Elements 5% S-Block Elements 5% Aldehyde Ketone 5% Solutions 5% Solid State 5% Chemical Thermodynamics 5% Ionic Equilibrium 3% Chemical Equilibrium 3% Surface Chemistry 3% Atomic Structure 2% Gaseous State 2% Transition Elements 2% Polymers 2% Nuclear Chemistry 2% Chemical Kinetics 2% Mole Concepts 2% Amines and Diazonium Salts 2% Biomolecules 2% Alkanes, Alkenes and Alkynes 2% Electrochemistry 2%

Maths - Inverse Trigonometric Functions  Weightage: 2% Circles and Family of Circles  Weightage: 6% Sequence and Series  Weightage: 5% Applications of Derivative  Weightage: 4% Limit and Continuity  Weightage: 3% Matrices and Determinants  Weightage: 4% Straight Lines and Pair of Straight Lines  Weightage: 2% 3-D Geometry   Weightage: 5% Probability and Statistics   Weightage: 7% Vector Algebra   Weightage: 5% Integration   Weightage: 8% (Definite + Indefinite integration) Complex Numbers   Weightage: 5% Parabola   Weightage: 3% Trigonometric Ratios   Weightage: 3% Logarithms   Weightage: 1% Quadratic Equations Theory of Equations   Weightage: 5% Sets, Relations and Functions   Weightage: 4% Differentiation  2% Permutation and Combination   Weightage: 2%. You should study this properly as concepts from this section will be needed in Probabilty Binomial Theorem   Weightage: 1% Locus Hyperbola   Weightage: 2% Ellipse   Weightage: 2% Fundamentals of Mathematics Solution of Triangle 1%

Physics - Units and Dimensions  Weightage: 2% Measurement of Errors  Weightage: 2% Vectors Kinematics  Weightage: 1% Newtons Laws of Motion  Weightage: 4% Friction Work, Energy and Power  Weightage: 5% Electrostatics  Weightage: 6% Current Electricity  Weightage: 7% Wave Optics  Weightage: 5% Ray Optics  Weightage: 6% Centre of Mass, Momentum and Collision  Weightage: 5% Rotational Dynamics  Weightage: 4% Simple Harmonic Motion  Weightage: 5% Fluid Mechanics  Weightage: 2  5%.  Wave Motion and String Waves  Weightage: 5% Magnetism  Weightage: 6% Heat & Thermodynamics  Weightage: 6%.Nuclear Physics  Weightage: 5% Modern Physics  Weightage: 5%, Circular Motion  Weightage: 1% Gravitation  Weightage: 1% Properties of Matter, Elasticity  Weightage: 2% Sound Waves Electromagnetic Induction  Weightage: 3% Alternating Current  Weightage: 1% Semiconductors and Electronic Devices 5%.

Hope this helps!!!!

12th class has more weightage in JEE Main exam. Generally, it has 40:60 ratio. 40% for 11th class and 60% for 12th class.

Below are the important chapters for JEE exam-

PHYSICS

Mechanics

Electricity and magnetism

Thermal physics

Fluids and waves and sound

Potentiometer-related experiments

Optics

Modern physics

CHEMISTRY

Physical Chemistry

Mole Concept

Atomic Structure

Organic Chemistry

General Organic Chemistry

Named Reactions

Organic Synthesis:

Inorganic Chemistry

MATHEMATICS

Calculus

Co-ordinate Geometry

Vectors (and 3D Geometry)

Algebra

Trigonometry