Hello,
Here is a simple chapter-priority list for CUSAT CAT for Maths, Physics, and Chemistry based on trends (frequency of questions and importance).

Maths High Priority
Algebra (Quadratic, Sequences)
Coordinate Geometry
Calculus (Limits, Derivatives)
Probability & Statistics

Medium Priority
Trigonometry
Vectors & 3D Geometry
Matrices & Determinants

Low Priority
Set Theory & Relations

Physics High Priority
Electrostatics & Current Electricity
Magnetism & EM Induction
Optics
Waves & Sound

Medium Priority
Heat & Thermodynamics
Modern Physics (Photoelectric, Atomic Models)

Low Priority
Units & Measurement

Chemistry High Priority
Physical Chemistry (Equilibrium, Thermodynamics)
Organic Functional Groups & Reactions
Inorganic Periodic Table & Chemical Bonding

Medium Priority
Electrochemistry
Coordination Compounds

Low Priority
Environmental Chemistry

This is based on past paper trends, but still prepare everything well.