Dear aspirant,

Yes, thorough knowledge of NCERT books of 11th and 12th standard are essential for a good score in IIT JAM. The following chapters of 11th and 12th standard NCERT books  are of utmost importance :

1. Physical World and Measurement
2. Kinematics
3. Laws of Motion
4. Work
5. Energy and Power
6. Electrostatics
7. Current electricity
8. Magnetic Effects of Current and Magnetism
9. Optics
10. Heat and Thermodynamics
11. Oscillations
12. Waves

For further assistance visit: https://university.careers360.com/articles/jam-syllabus

Hope this helped.

Thank you.