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Physics

Nuclei

A Physics chapter of the NEET syllabus, and how to practise it for the computer-based exam.

Exam rules change between cycles. Confirm dates, syllabus and pattern against NTA's official site. We are not NTA.

Weightage: what the paper actually did

Nuclei carried 3 questions in the NEET 2026 paper. One paper is a data point, not a destiny: NTA moves weight between chapters every cycle, which is why the weightage tables deserve care. The stable facts are the paper's shape: 180 questions, 720 marks, +4 right, −1 wrong.

Sample PYQs from this chapter

Real questions NTA asked from Nuclei, with the answer and the working. Try before you peek.

Question 1 · NEET 2020

When a uranium isotope 2^{2}3^{3}5^{5}9_{9}2_{2}U is bombarded with a neutron, it generates 8^{8}9^{9}3_{3}6_{6}Kr, three neutrons and
  1. A.9^{9}1^{1}4_{4}0_{0}Zr
  2. B.1^{1}0^{0}1^{1}3_{3}6_{6}Kr
  3. C.1^{1}0^{0}3^{3}3_{3}6_{6}Kr
  4. D.1^{1}4^{4}4^{4}5_{5}6_{6}Ba
Answer and explanation

Answer: D

The nuclear reaction is 92235U+01n→3689Kr+3 01n+56144Ba^{235}_{92}U + ^1_0n → ^{89}_{36}Kr + 3\ ^1_0n + ^{144}_{56}Ba. The mass and charge numbers must be conserved, so the remaining product is 56144Ba^{144}_{56}Ba. Chapter: Nuclei.

Question 2 · NEET 2026

An unknown nucleus has a nuclear density of 2.29×10172.29 \times 10^{17} kg/m3^3 and mass of 19.926×10−2719.926 \times 10^{-27} kg. Its mass number AA is approximately: (Take R0=1.2×10−15R_0 = 1.2 \times 10^{-15} m, 4π=12.564\pi = 12.56)
  1. A.12
  2. B.20
  3. C.16
  4. D.19
Answer and explanation

Answer: A

Using density = mass/volume with volume =43πR3= \frac{4}{3}\pi R^3 and R=R0A1/3R = R_0 A^{1/3}, we get 43πR03A=mρ\frac{4}{3}\pi R_0^3 A = \frac{m}{\rho}. Solving, A=mρ⋅34πR03=19.926×10−27×32.29×1017×12.56×(1.2×10−15)3≈12A = \frac{m}{\rho}\cdot\frac{3}{4\pi R_0^3} = \frac{19.926\times10^{-27}\times3}{2.29\times10^{17}\times12.56\times(1.2\times10^{-15})^3} \approx 12.

How to practise Nuclei

Chapter by chapter, against real past-paper questions, on a screen: NEET is computer based from 2027. Read the chapter once, then attempt its PYQs until your accuracy stops climbing, and let the wrong answers tell you which lines to reread. If the chapter keeps refusing to stick, that has its own guide. There is also a free NEET mini mock with answers.

Nearby Physics chapters

Questions

How many questions did Nuclei have in NEET 2026?

Nuclei carried 3 questions in the NEET 2026 paper. Weightage shifts between cycles, so treat it as a probability, not a promise.

Where can I practise Nuclei PYQs for NEET?

Explore available chapter-wise NEET practice in BrainIt, free until the 2027 exam. Review explanations and track chapter accuracy to guide your revision. Sample questions from this chapter are on this page.

Is Nuclei important for NEET 2027?

It is part of the Physics syllabus the paper draws from, and NEET 2027 is computer based, so practise it on a screen. Your own accuracy in the chapter matters more than any weightage table: a heavy chapter you already score well on needs less time than a light one you keep missing.

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