Hello,

In JEE Main questions are asked from each and every topic, be it chemistry in everyday life or Environmental Chemistry. So read all topics.

But I would say that from some Topics they ask a question every year so don't forget to read about the following topics.

Chemical Bonding, Specially Molecular Orbital Theory

Redox Reactions, Balancing and Disproportionation reaction, Properties of H2O2

General concepts or Organic Chemistry

Electrochemistry

p-Block elements

Aldehyde Ketone and Carboxylic acids.

This is some of the most important Topics and You can expect at least some questions from Each topic.