In order to get a good score in jee main, you need to cover all the topics.

According to me, the most important topics are:-

• Oxygen-containing compounds. Especially name reactions in oxygen-containing compounds.Sometimes direct questions also come from these reactions.
• Nitrogen-containing compounds.
• Isomerism, especially stereo. Coordination Chemistry Isomerism comes in this too.
• Substitution reactions in aromatic compounds.
• Tests for the detection of the organic compounds.
• Carbonyl compounds, Aromatic Compounds, Alcohols.

All the very best and good luck.

oxygen-containing compounds major questions come from reactions involving oxygen-containing compounds 

nitrogen containing compounds their reactions and applications 

isomerism and their important properties 

substitution reaction in aromatics compounds

test for the detection of the organic compounds

resonance and mesomeric effects 

hyperconjugation

carboxylic acid 

alcohols and ethers 

haloarenes and phenols 

thanks!!!!