For Class 12th, if you're preparing for JEE while ensuring a strong NCERT foundation, here are some of the best guides with excellent theory explanations:

Physics

1. Concepts of Physics by H.C. Verma (Vol 1 & 2) – Best for conceptual clarity and problem-solving.

2. Understanding Physics by D.C. Pandey (Arihant Series) – Topic-wise coverage with great theory and examples.

3. NCERT Exemplar & Physics NCERT (for basics) – Essential for board exams and JEE base concepts.

Chemistry

1. NCERT Chemistry (Both Physical & Organic) + NCERT Exemplar – Must for theory and direct JEE questions.

2. Modern’s ABC of Chemistry – Great for detailed theory aligned with NCERT.

3. Physical Chemistry by P. Bahadur – For numerical problems and JEE preparation.

4. Organic Chemistry by Morrison & Boyd (Optional) – For deeper conceptual clarity.

5. Inorganic Chemistry by J.D. Lee (adapted version for JEE) – Good for conc

eptual understanding.

Mathematics

1. NCERT Mathematics – Base book for boards and JEE fundamentals.

2. Cengage Mathematics Series – Provides topic-wise theory and a variety of problems.

3. Arihant’s Skills in Mathematics by Amit M Agarwal – Good for understanding advanced concepts.

4. Problems in Calculus of One Variable by I.A. Maron – For strong calculus preparation.

If you're looking for one-stop solutions for JEE + NCERT theory, Arihant’s and Cengage’s books provide excellent detailed explanations.