The Nuclei NCERT PDF hosted here is your single canonical source for Class 12 Physics Chapter 13 Nuclei. The Nuclei NCERT PDF matches the 2026-27 printed textbook page-for-page, so any section reference in CBSE blueprints points to the same paragraph in this Nuclei NCERT PDF. Hit download below.
- CBSE Weightage: 3 to 4 marks
- JEE Main Weightage: 2 to 3% (1 question per paper)
- NEET Weightage: 2 to 3 questions per year
Both downloads of the Nuclei NCERT PDF on this page are free and updated for the 2026-27 NCERT syllabus.
This NCERT Book PDF is curated by subject experts at Collegedunia, mapped to the 2026-27 new edition, and refined against the last five years of CBSE Board, JEE Main, and NEET papers.
NCERT Section-by-Section Breakdown for Class 12 Physics Chapter 13 Nuclei
The chapter spans roughly 30 pages and breaks into seven sections plus a summary and exercises tail. The table maps each section to its page range and the most exam-relevant idea inside it, so students can decide which sections to skim and which to read line by line.
| Section | Title | Pages | Key Exam-Relevant Idea |
|---|---|---|---|
| 13.1 | Introduction | 1 to 2 | Nucleus is ~10,000 times smaller than the atom; carries almost all the mass |
| 13.2 | Atomic Masses and Composition of Nucleus | 3 to 7 | 1 u = 931.5 MeV/c2; isotopes, isobars, isotones |
| 13.3 | Size of the Nucleus | 8 to 10 | R = R0 A1/3, R0 = 1.2 fm; nuclear density independent of A |
| 13.4 | Mass-Energy and Nuclear Binding Energy | 11 to 17 | BE/A curve peaks at Fe-56 (~8.79 MeV/nucleon) |
| 13.5 | Nuclear Force | 18 to 19 | Short-range, charge-independent, saturated |
| 13.6 | Radioactivity | 20 to 24 | N(t) = N0 e-λt; T1/2 = 0.693/λ |
| 13.7 | Nuclear Energy | 25 to 28 | Fission Q ~ 200 MeV; D-T fusion Q ~ 17.6 MeV |
| - | Summary and Exercises (31 Qs) | 29 to 30 | Recap + practice numericals |
Sections 13.4, 13.6, and 13.7 together carry more than 80% of every previous year question from this chapter. Sections 13.1 and 13.5 are quick reads; 13.2 and 13.3 are short but hold the two constants every numerical needs.
Nuclei Video Chapter Walkthrough
Source: Next Toppers - 12th Science on YouTube
Intext Example Inventory for Nuclei Class 12 Physics
The chapter has around 10 intext Examples placed at the point where each new formula appears. Solving them in order is the cleanest way to internalise the chapter; CBSE often paraphrases them in 2-mark and 3-mark questions.
| Example | Sub-topic Tag | What it Covers |
|---|---|---|
| 13.1 | Atomic mass unit | Convert 1 u into kg and MeV |
| 13.2 | Nuclear size | Apply R = R0 A1/3 for given A |
| 13.3 | Nuclear density | Show density is independent of A |
| 13.4 | Binding energy | Compute BE of He-4 (28.3 MeV) |
| 13.5 | BE per nucleon | Use BE/A to compare stability |
| 13.6 | Half-life | Find λ from given T1/2 |
| 13.7 | Activity | Convert curie to becquerel and back |
| 13.8 | Mean life | Relate τ and T1/2 |
| 13.9 | Fission energy | Q-value of one U-235 fission event |
| 13.10 | Fusion energy | Compute Q for D-T reaction |
Examples 13.4, 13.6, and 13.9 are the three you should reproduce from memory before a board exam.
How to Read Chapter 13 Nuclei in the Right Sequence
This is a numerical-first chapter. The three-pass plan below squeezes maximum exam yield from the 30-page PDF in roughly 5 to 6 hours of study time.
- Pass 1, Skim (45 minutes): Read 13.1, the section headings, every boxed formula, and the BE/A curve in 13.4. No numericals yet.
- Pass 2, Detailed read (3 hours): Read sections 13.2 to 13.7 line by line. Pause at every Example, work it on paper, then compare.
- Pass 3, Exercises (2 hours): Attempt all 31 end-of-chapter Exercises in order. Mark the binding energy, half-life, and fission Q-value problems.
- Day-before-exam: Re-skim the BE/A curve and the U-238 to Pb-206 decay-chain step count.
2026-27 Edition Changes in Class 12 Physics Chapter 13 Nuclei
The current 2026-27 NCERT print of Nuclei is largely unchanged. The chapter still runs seven sections and keeps the BE/A curve, the U-235 fission discussion, and the radioactive decay law derivation.
What the new edition kept: all seven sections (13.1 to 13.7), the BE/A plot with the Fe-56 peak, R = R0 A1/3, the full decay law derivation, and both fission and fusion Q-value calculations. What was trimmed earlier: detailed nuclear reactor treatment, controlled thermonuclear fusion engineering, and the radioactive series tables. The numerical core is intact.
Every CBSE 3-mark Nuclei numerical from 2022 to 2025 was drawn from the sections that survived the syllabus revision.
Chapter Weightage Bar Chart: Where Nuclei Sits in Class 12 Physics
The visual below maps the typical CBSE Class 12 Physics marks distribution across all 14 chapters of the NCERT book, averaged over the last five board papers.
Print-Friendly Version Tips for the Nuclei NCERT Book PDF
The 30-page PDF does not need to be printed in full. Students short on printer ink can use the trimmed plan below to cover everything the exam tests on roughly 18 to 20 sheets.
Print double-sided in greyscale to halve paper use; the BE/A curve and fission schematic reproduce clearly.
Nuclei Top 5 Formulae from the NCERT Chapter
The five formulae below drive every numerical in the chapter. The full master table with units and the "when to use which" decision tree is on the dedicated Collegedunia Formula Sheet.
| Quantity | Formula |
|---|---|
| Mass-energy equivalence | E = mc2; 1 u = 931.5 MeV/c2 |
| Binding energy | BE = Δm · c2 |
| Nuclear radius | R = R0 A1/3, R0 ≈ 1.2 fm |
| Decay law and half-life | N(t) = N0 e-λt; T1/2 = 0.693/λ; τ = 1/λ |
| Nuclear energy Q-values | Qfission ≈ 200 MeV (U-235); QDT ≈ 17.6 MeV |
Full master table: Nuclei Class 12 Physics Formula Sheet
Top 3 PYQ Trends in Class 12th Physics Chapter 13 Nuclei
Three question patterns dominate recent papers. The full year-by-year question map across CBSE, JEE Main, and NEET sits on the NCERT Solutions page.
- Half-life and radioactive decay numerical, appeared in NEET 2024 and CBSE 2025. Typically asks for the fraction remaining after n half-lives, or the decay constant from a given T1/2.
- Binding energy per nucleon curve interpretation, appeared in JEE Main 2025 and NEET 2023. Tests whether students can identify the Fe-56 peak and explain why fission and fusion both release energy.
- Fission or fusion Q-value, appeared in CBSE 2024 and NEET 2024. Asks for the energy released per nucleus from given mass defects.
Full year-wise map: Nuclei Class 12 Physics NCERT Solutions
More Nuclei Physics Class 12 Resources
NCERT Book PDF for Class 12 Physics: All Chapters
Other Class 12 Physics NCERT Book PDFs you can grab as free downloads:
| Chapter | Resource |
|---|---|
| Chapter 1 | Electric Charges and Fields NCERT PDF |
| Chapter 2 | Electrostatic Potential and Capacitance NCERT PDF |
| Chapter 3 | Current Electricity NCERT PDF |
| Chapter 4 | Moving Charges and Magnetism NCERT PDF |
| Chapter 5 | Magnetism and Matter NCERT PDF |
| Chapter 6 | Electromagnetic Induction NCERT PDF |
| Chapter 7 | Alternating Current NCERT PDF |
| Chapter 8 | Electromagnetic Waves NCERT PDF |
| Chapter 9 | Ray Optics and Optical Instruments NCERT PDF |
| Chapter 10 | Wave Optics NCERT PDF |
| Chapter 11 | Dual Nature of Radiation and Matter NCERT PDF |
| Chapter 12 | Atoms NCERT PDF |
| Chapter 14 | Semiconductor Electronics NCERT PDF |
Nuclei NCERT PDF: available above as a free PDF download, fully aligned to the 2026-27 NCERT release.
Nuclei NCERT PDF - Frequently Asked Questions
Ques. Where can I download the Nuclei NCERT PDF for free?
Ans. You can download the Nuclei NCERT PDF directly from this page. Both the Normal and HD versions are free and reflect the 2026-27 official NCERT print.
Ques. Is this Nuclei NCERT PDF aligned with the 2026-27 CBSE syllabus?
Ans. Yes. This page reflects the current 2026-27 syllabus for Class 12 Physics. All seven sections (13.1 to 13.7) including the binding energy curve, decay law, and fission/fusion content are retained in the new NCERT edition.
Ques. How many pages is the Class 12th Physics Nuclei NCERT Book PDF?
Ans. The Nuclei NCERT PDF NCERT Book PDF runs approximately 30 pages and covers atomic masses, nuclear size, mass-energy and binding energy, the nuclear force, radioactivity, and nuclear energy, plus around 10 intext Examples and 31 end-of-chapter Exercises.
Ques. What is the CBSE, JEE, and NEET weightage of Nuclei?
Ans. CBSE Board allocates about 3 to 4 marks to Nuclei NCERT PDF every year. JEE Main devotes roughly 2 to 3% of the paper (typically one binding energy or half-life numerical), and NEET asks 2 to 3 questions per year, most often on radioactivity or fission/fusion energy.
Ques. Which sections of Chapter 13 Nuclei matter the most for the exam?
Ans. Section 13.4 (Mass-Energy and Nuclear Binding Energy), Section 13.6 (Radioactivity), and Section 13.7 (Nuclear Energy) together account for more than 80% of previous year questions from this chapter. Read these line by line; the others can be skimmed.
Ques. Does the 2026-27 NCERT edition still include nuclear fission and fusion?
Ans. Yes. Section 13.7 in the new NCERT edition still covers both fission of U-235 (Q ~ 200 MeV per nucleus) and D-T fusion (Q ~ 17.6 MeV), along with the binding energy curve argument that explains why both release energy.
Ques. Where can I find solved answers to the 31 Exercises in Chapter 13 Nuclei?
Ans. Detailed step-by-step answers to all 31 end-of-chapter Exercises with marking-scheme annotations are on the Collegedunia Nuclei NCERT PDF NCERT Solutions page linked from the Related Resources block above.
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