Hello Vaibhav

In order to get a good score in NEET, you need to cover all the topics and all the concepts.So all the chapters are equally important.But yes there are some concepts you should never ignore.

Oxygen containing compounds.Specially name reactions in oxygen containing compounds.Sometimes direct questions also come from these reactions.

Nitrogen containing compounds

Isomerism

Substitution reactions in aromatic compounds

Tests for the detection of the organic compounds

So these are very important.But again I remind you that all the concepts should be covered.Never leave anything before going to exam.