Jai,

I will give you a quick guide for PCM

FOR

1)Physics- 

• Dimensions
• Kinematics
• Fluid mechanics 
• SHM
• KINETIC THEORY OF GASES 
• ELECTROSTATICS 
• MORDEN PHYSICS 
• OPTICS( LENS AND WAVE) 
• INTERFERENCE AND DIFFRACTION 
• POLARISATION
• DUAL MATTER WAVE
• PHOTOELECTRIC EFFECT. 
• THERMODYNAMICS 

2) CHEMISTRY 

• THERMODYNAMICS 
• SOLUTIONS 
• KINECTICS
• ORGANIC 
• INORGANIC 
• COORDINATION COMPOUND 
• KINETIC THEORY OF GASES 
• Ionic and Chemical Equilibrium 
• Atomic Structure 
• Electrochemistry
• Solid State 
• Surface Chemistry 

3) Mathematics 

• Sets,  Relation and function 
• Vector 3d
• Complex
• Matrices and Determinants
• Permutations amd Combinations 
• Binomial Theorem 
• AP, GP, HP
• Conic Section
• Differential Equation 
• Integration 
• Limit and continuity 
• Statics and Probability. 

These are topics which covers the major portion of the paper of JEE. 

Hope it will help. 

And for remembering structures you need to know tge besic structures.  Try remembering basic structures like alkyl, benzyl, amino, cyano etc. 

You can learn it from YouTube or you can try BYJUS it will definitely help. 

And rarely 1 or 2 question comes from structure parts so need to worry if in case you wanna skip it. 

If you learn from byjus you will definitely remember structures.