The Class 12 Physics Chapter 13 Nuclei PYQ compilation has 165 board-paper questions across 24 years (2003 to 2026), sorted by marks (1 to 5) and by year (latest first). The PDF mirrors the 2026-27 CBSE pattern so that every section of the question paper is represented.
- 1-mark MCQs: 46 questions, mostly post-2023 when CBSE switched to Section A objective format.
- 2 and 3-mark VSA/SA: 44 and 75 questions respectively, focused on mass defect and binding-energy numericals, radioactive-decay half-life problems, and nuclear-fission/fusion energy calculations.
- 5-mark long answers: 4 questions, almost every year features one of the chapter's flagship derivations paired with a numerical.
Every question in this Class 12 Physics Nuclei PYQ compilation is sourced from CBSE board papers (Delhi, Outside Delhi, Foreign, Compartment) and cross-checked against the official mark scheme, with near-duplicate questions removed by a 0.85 similarity threshold.
What the Nuclei Previous Year Questions Cover
The 165-question compilation maps every concept the NCERT chapter introduces. The PDF gives heavy coverage to mass defect and binding-energy numericals, radioactive-decay half-life problems, and nuclear-fission/fusion energy calculations, which dominate the 3 and 5-mark bands across the 2003 to 2026 window. The 1-mark MCQ block covers conceptual definitions, formula identification, and graph-interpretation questions added since 2023.
Class 12 Physics Chapter 13 Nuclei PYQ
Source: NCERT Wallah on YouTube
Marks-wise Distribution of the Nuclei PYQs
The table below shows how the 165 questions split across the five CBSE marks bands. Use this to plan how much weight to give each band when you revise.
| Marks | Questions | Total Marks | CBSE Section | Type |
|---|---|---|---|---|
| 1 mark | 46 | 46 | Section A | MCQ + Assertion-Reason |
| 2 mark | 44 | 88 | Section B | VSA |
| 3 mark | 75 | 225 | Section C | SA |
| 4 mark | 1 | 4 | Section D | Case Study |
| 5 mark | 4 | 20 | Section E | Long Answer |
Year-wise Spread of Class 12 Physics Chapter 13 PYQs
The compilation pulls questions from 24 distinct CBSE board years. Post-2023 papers contribute a significant share because the MCQ-heavy format multiplied the 1-mark count.
- 2026: Latest sets across 55-1-X, 55-3-X, 55-5-X. Fresh MCQ wording for nuclei concepts plus a 5-mark OR question.
- 2024 to 2025: The largest contribution years, with MCQ banks across 55-1, 55-2, 55-3, 55-4, 55-5 sets and Compartment papers.
- 2020 to 2023: Pandemic-period reduced-syllabus papers but still feature the chapter's flagship derivations.
- 2003 to 2019: Heritage long-answer questions that remain relevant to the current pattern.
Topic Frequency in the Nuclei Board Paper Questions
The 165 questions cluster into six topic buckets. The table below ranks them by how often CBSE has set a question on that topic between 2003 and 2026.
| Rank | Topic Cluster | Frequency | Typical Marks Band |
|---|---|---|---|
| 1 | Binding energy and mass defect | ~24 per cent | 2, 3, 5 mark |
| 2 | Radioactive decay law and half-life | ~22 per cent | 2 and 3 mark |
| 3 | Alpha, beta, gamma decay | ~17 per cent | 1, 2, 3 mark |
| 4 | Nuclear fission and fusion | ~16 per cent | 3 and 5 mark |
| 5 | Nuclear composition and size | ~12 per cent | 1 and 2 mark |
| 6 | BE per nucleon curve | ~9 per cent | 2 and 3 mark |
Marks-Band Attempt Strategy for the Chapter 13 PYQs
The 165 PYQs are organised marks-ascending inside the PDF so that you can practice in the exact order the CBSE paper presents them.
- 1-mark MCQs: Spend no more than 45 seconds each. 90 seconds is the danger threshold, if you cross it, mark and move on.
- 2-mark VSA: One formula plus a one-line derivation or numerical. Aim for 3 minutes.
- 3-mark SA: Two sub-parts. Typical structure: a derivation plus a numerical, or a definition plus a sketch.
- 5-mark long answer: Two main parts ("a" and "b") with an OR alternative. Allocate 12 to 15 minutes including the figure.
Recent CBSE Trend: 2024 to 2026 Pattern Shift
Three things have changed in the last three CBSE cycles that the Class 12 Physics chapter 13 previous year questions now reflect:
- Section A (MCQ + Assertion-Reason) takes 20 per cent of the paper, up from 0 in pre-2023 patterns. The PYQ compilation has 46 such questions.
- Case-study (Section D, 4 marks) appears in select Physics papers and the chapter-wise PDF preserves any that fell on Chapter 13.
- 5-mark questions almost always come with an OR alternative. The Nuclei PYQ PDF preserves both branches so you can revise both options.
Common Mistakes in the Nuclei Board Questions
- Writing the radioactive-decay law as N = N0 e+λt instead of N = N0 e-λt.
- Confusing half-life T1/2 with mean life τ: T1/2 = τ ln(2) ≈ 0.693 τ.
- Computing mass defect without converting amu to MeV (1 amu = 931.5 MeV).
- Saying fission releases more energy per nucleon than fusion (fusion releases more per nucleon, but fission releases more per reaction).
- Using R = R0 A instead of R = R0 A1/3 for the nuclear radius.
Student Pulse on Nuclei PYQ Practice
- 65 per cent said the binding-energy-per-nucleon curve interpretation is the most-frequent 3-mark question across 2003 to 2026.
- 51 per cent reported gaining 4 to 5 marks after solving every half-life PYQ in this PDF.
- 38 per cent said an alpha/beta/gamma identification MCQ appeared in their CBSE 2026 paper.
- Average time to complete all questions: spread across 5 study sessions.
How These PYQs Pair with the Other Chapter 13 Resources
Solving previous year questions in isolation gives you only half the prep. Pair the PYQ PDF with the matching concept and formula resources for the same chapter.
- Stuck on a derivation? Open the NCERT Solutions for Chapter 13 Nuclei for step-by-step worked answers to every NCERT back exercise.
- Need quick formula recall? The Nuclei Formula Sheet compiles all key formulas and constants for last-day revision.
- Concept revision? The Nuclei Notes page covers definitions, derivations, and diagrams.
- Extra practice? The NCERT Exemplar Solutions for Chapter 13 add deeper-level problems beyond the back exercises.
How to Use the Nuclei PYQ PDF Most Effectively
The 165 questions are sequenced for a three-pass revision plan:
- Pass 1 (Day 1 to 2): Attempt every 1-mark MCQ (46 questions). Mark every wrong attempt and re-read the relevant NCERT paragraph.
- Pass 2 (Day 3 to 5): Solve all 2-mark and 3-mark VSA/SA questions (119 total). Time yourself: 3 minutes per 2-mark, 5 minutes per 3-mark.
- Pass 3 (Day 6 to 10): Tackle the 4 five-mark long answers. Each one is essentially a board-paper Section E in miniature: write the full derivation, then the numerical, then verify direction and units.
The PDF's table of contents (page 1) is hyperlinked: click on any marks band to jump to that section.
All Class 12 Physics Chapter PYQ PDFs
Every other Class 12 Physics chapter has its own PYQ compilation built the same way (2003 to 2026, marks-sorted, year-tagged).
| Chapter | Topic | Previous Year Questions |
|---|---|---|
| Ch 1 | Electric Charges and Fields | PYQ PDF |
| Ch 2 | Electrostatic Potential and Capacitance | PYQ PDF |
| Ch 3 | Current Electricity | PYQ PDF |
| Ch 4 | Moving Charges and Magnetism | PYQ PDF |
| Ch 5 | Magnetism and Matter | PYQ PDF |
| Ch 6 | Electromagnetic Induction | PYQ PDF |
| Ch 7 | Alternating Current | PYQ PDF |
| Ch 8 | Electromagnetic Waves | PYQ PDF |
| Ch 9 | Ray Optics and Optical Instruments | PYQ PDF |
| Ch 10 | Wave Optics | PYQ PDF |
| Ch 11 | Dual Nature of Radiation and Matter | PYQ PDF |
| Ch 12 | Atoms | PYQ PDF |
| Ch 13 | Nuclei | This page |
| Ch 14 | Semiconductor Electronics | PYQ PDF |
Also Check: NCERT Solutions for Class 12 Physics (All 14 Chapters) · Class 12 Physics Formula Sheet · Class 12 Physics Resource Hub
Class 12 Physics Chapter 13 Nuclei PYQ FAQs
Ques. How many previous year questions are there in the Class 12 Physics Chapter 13 PYQ PDF?
Ans. The PDF contains 165 previous year questions from CBSE board papers between 2003 and 2026, sorted by marks (1 to 5) and then by year (latest first). Near-duplicate questions across sets and years have been removed at a 0.85 similarity threshold so the same question is never asked twice.
Ques. Are the Nuclei PYQs based on the 2026-27 CBSE syllabus?
Ans. Yes. Every question is mapped to the 2026-27 CBSE Class 12 Physics syllabus. Questions from the pre-2023 long-form pattern are still included because the underlying concepts of the chapter are unchanged in the current syllabus.
Ques. How is this PYQ PDF different from a standard CBSE sample paper?
Ans. A sample paper gives you one paper at a time. This PDF stitches 24 years of questions across every set and region (Delhi, Outside Delhi, Foreign, Compartment) for Chapter 13 alone, so you can see the actual frequency of topics and the standard CBSE phrasings of each concept.
Ques. Which CBSE board years are covered in the Class 12 Physics Chapter 13 PYQ compilation?
Ans. The compilation covers 24 years from 2003 to 2026. Within each year, the Delhi, Outside Delhi, Foreign, and Compartment sets are included.
Ques. Are MCQs included in the Nuclei PYQ PDF?
Ans. Yes. 46 of the 165 questions are 1-mark MCQs, mostly from 2023 onwards when CBSE introduced the Section A objective format. The PDF also includes assertion-reason questions that appeared from 2024 onwards.
Ques. Where can I download the Nuclei chapter 13 PYQ PDF for free?
Ans. The full Nuclei PYQ PDF is available for free download from the PDF button at the top of this page. No registration is needed.
Ques. How should I use the previous year questions to revise Chapter 13 in the last 10 days before boards?
Ans. Follow the three-pass plan: Day 1 to 2 attempt all 46 MCQs, Day 3 to 5 attempt all 119 short answers, Day 6 to 10 attempt all 4 long answers under a 12-minute timer. The PDF's hyperlinked table of contents lets you jump between marks bands.
Ques. Which sub-topics of Nuclei appear most often in CBSE board papers?
Ans. From the 165-question sample, the top six topic clusters are: Binding energy and mass defect (~24 per cent), Radioactive decay law and half-life (~22 per cent), Alpha, beta, gamma decay (~17 per cent), Nuclear fission and fusion (~16 per cent), Nuclear composition and size (~12 per cent), and BE per nucleon curve (~9 per cent).
Ques. Does the Class 12 Physics Chapter 13 PYQ PDF include answers or just the questions?
Ans. The PDF contains only the questions, sorted by marks and year, so you can attempt them as a practice paper. For step-by-step solutions, open the matching NCERT Solutions page or refer to the official CBSE mark scheme for the relevant year.
Ques. What is mass defect?
Ans. Mass defect Δm is the difference between the sum of the masses of the individual nucleons and the actual mass of the nucleus. The missing mass is converted to binding energy through Einstein's relation E = Δm c², where Δm is in kilograms and c is the speed of light.
Ques. How is binding energy defined?
Ans. Binding energy of a nucleus is the energy required to disintegrate it completely into its constituent protons and neutrons. It is computed as BE = Δm × 931.5 MeV (with Δm in atomic mass units). The binding energy per nucleon indicates the stability of the nucleus.
Ques. What are alpha, beta, and gamma decay?
Ans. Alpha decay emits a helium-4 nucleus (²He4) and reduces both A and Z. Beta-minus decay emits an electron and an antineutrino, increasing Z by 1. Beta-plus decay emits a positron and a neutrino, decreasing Z by 1. Gamma decay emits a high-energy photon with no change in A or Z.
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