Hi,

Yes you can get 100 marks in jee mains by studying only the ncert. If you are ready to put some more efforts you can easily score above 80 in chemistry if you are thorough with ncert, and have practised almost every question in it. Many questions are directly asked from the ncert in mains. However, I find the ncert mathematics books to be a bit subpar in comparison to the level of questions asked in jee mains, the ncert physics books are good and cover the basics but lack a lot of questions for practice. Nevertheless, you can easily score above 100 marks just with ncert books.

All topics which are only for JEE Main(not in the syllabus of JEE Advanced) are very important. Students generally skip them but they are very scoring and from each chapter at least one question is asked.

List of that chapters:

Physics:

1. Semiconductor
2. Communication systems.
3. Logic Gates
4. Diffraction and Polarization
5. Bulk modulus and modulus of rigidity

For these chapters you need to solve questions and be aware of terms used in chapters. You will find that problems from these chapters are mostly formula based just practice them properly.

Chemistry:

1. F Block.

2. Environmental chemistry

3. Chapter Hydrogen

4. Biomolecules.

5. Surface chemistry

For chemistry revise all theory thoroughly and make sure you are aware of the names of chemicals. Solving more problems will help you in remembering things.

Hope this helps.

Good luck.