Class 12 Physics — Chapter 12: Atoms
90 practice questions · 30 Easy · 30 Medium · 30 Hard
Practise Class 12 Physics Chapter 12, "Atoms", with 90 NCERT-aligned multiple-choice questions. The set is split into 30 Easy, 30 Medium and 30 Hard questions, so you can warm up on the fundamentals and then push into the exam-level problems that separate top scorers in CBSE Board exams, JEE Main, JEE Advanced and NEET UG.
"Atoms" is one of the chapters where numerical problem-solving, derivations and conceptual application really pays off. Each MCQ on this chapter is timed and uses exam-grade marking (+2 correct, −1 wrong, 0 skipped), training the same accuracy-under-pressure that real papers demand. Every question carries a short explanation, so a wrong answer becomes a quick lesson rather than a dead end — the fastest way to close gaps before a test.
Use this chapter as targeted revision: attempt the Easy set first to confirm your basics on Atoms, then move to Medium and Hard to test application and problem-solving. Your accuracy, streaks and XP save automatically, and the chapter feeds into your overall Class 12 Physics mastery score. A few sample questions are shown below; sign in free to practise all 90.
Key concepts: Atoms (Class 12 Physics)
This chapter covers Rutherford's nuclear model, Bohr's model of the hydrogen atom, energy levels, and the hydrogen spectral series.
- Rutherford's model
- The α-scattering experiment showed a tiny, dense, positive nucleus with electrons around it; but it could not explain stability.
- Bohr's postulates
- Electrons orbit in stationary states with quantised angular momentum (L = nh/2π); energy is radiated only on jumping between levels.
- Energy levels
- For hydrogen, Eₙ = −13.6/n² eV; the ground state (n=1) is most stable, energy increases (toward 0) with n.
- Spectral emission
- A photon of energy hν = E_initial − E_final is emitted when an electron falls to a lower level.
- Spectral series
- Lyman (UV, to n=1), Balmer (visible, to n=2), Paschen (IR, to n=3), etc., given by the Rydberg formula.
Key formulas — Atoms
💡 Exam tips for Atoms
- Energy is negative and increases toward zero as n increases; the electron is least bound at high n.
- Match the series to the final level: Lyman→n=1 (UV), Balmer→n=2 (visible), Paschen→n=3 (IR).
Sample questions
Bohr's model: angular momentum is:
L = nℏ.
Energy of nth Bohr orbit (H atom):
Negative — bound state.
Lyman series corresponds to transitions to:
Ground state — UV region.
Atoms — FAQs
What are the key concepts in Class 12 Physics Atoms?+
This chapter covers Rutherford's nuclear model, Bohr's model of the hydrogen atom, energy levels, and the hydrogen spectral series. Key ideas include Rutherford's model, Bohr's postulates, Energy levels, Spectral emission, Spectral series.
What does Class 12 Physics Chapter 12 (Atoms) cover on XamBaaz?+
It covers 90 NCERT-aligned MCQs on "Atoms" — 30 Easy, 30 Medium and 30 Hard — each with a timed quiz and an instant explanation, suitable for CBSE Board exams, JEE Main, JEE Advanced and NEET UG.
Are these "Atoms" questions free to practise?+
Yes — sign in with Google to practise "Atoms" free. Full unlimited access is ₹999/year (limited-time launch price), with no per-chapter charges.
How should I revise "Atoms" for the exam?+
Start with the Easy quiz to confirm your fundamentals, then attempt Medium and Hard for application-level practice. Review each explanation, retry the questions you miss, and track your accuracy on this chapter until it is consistently high.
Practise all 90 questions free
Timed quizzes, instant scoring, streaks and XP. Sign in with Google — no card needed.
Start this chapter free →