Hi aspirant.Most of the questions are from a few chapters and topics. The important topics for the last minute revision of aiims are:-

a) Physics: 

    Electromagnetism(all the chapters)

    Modern Physics (focus on semiconductors and communications)

    SHM and Waves ( including wave optics)

    Force

b) Chemistry:

    Chemical Bonding

    Atomic structure

    General Organic Chemistry

    Electrochemistry

    p-block

c) Biology:

    Genetics

    Reproduction (Humans and Plants)

    Mineral nutrition in plants

    Five kingdom classification (focus on plants)

    Ecology(all chapters)