Based on analysis of previous years exam papers, few topics are considered to have more weightage than the rest of the topics. . In Chemistry, Transition Elements and Coordination Chemistry, Periodic Table and Representative elements take 3 questions slot. Thermodynamics and Gaseous state, Atomic structure, Chemical Bonding, Chemical and Iconic Equilibrium, Solid State and Surface Chemistry and Nuclear Chemistry and Environment get 2 questions slot eacch and the remaining get 1 question each. . For complete breakdown, please read our article: https://engineering.careers360.com/articles/jee-main-syllabus-weightage . and for the entire syllabus, read our page: https://engineering.careers360.com/articles/jee-main-chemistry-syllabus . With less than a month for the exam, it might be difficult to prepare notes and start from the scratch. Our JEE Mains Knockout package can help you with the same: https://learn.careers360.com/knockout-jee-main-april/ . Alternatively, you can refer and prepare from books like:

NCERT Books

Modern Approach to Chemical Calculations by R.C Mukherjee

Organic Chemistry by OP Tandon

Concept of Physical Chemistry by P Bahadur

Concise Inorganic Chemistry by J D Lee

Physical Chemistry by P.W Atkins

Organic Chemistry by Morrison and Boyd