In comedk ug major portion is from class 12 .
All the chapters from class 12 are important in all three subjects
In class 11 i suggest you to focus on following topics
Physics:-shm,wpe,thermal properties,heat and calorimetry,kinematics.
Chem:-s bock,bonding,mole,purification,equilibrium
Maths:-ap gp,reasoning,complex
I am providing you some questions from 2016 this will give you better idea