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Chemistry - Structure of Atom

Practise 251 JEE Main previous year questions on Structure of Atom, compiled from papers spanning 2002 to 2026. Each question is pulled directly from the actual exam paper it appeared in, so you're practising in the exact style and difficulty JEE Main tests.

Structure of Atom has been asked in 25 of the 25 years of JEE Main papers analysed (2002–2026), with 252 questions in all. 46% of them were easy, 46% moderate and 8% tough. Most of its questions came from 2023, with 29 questions that year. In the last three years (2024–2026) it had 65 questions across 49 papers, about 1.3 per paper.

The chapter's 8 topics are not weighted equally: Quantum mechanical model (72 questions, 29%), Dual Behaviour of Matter and Heisenberg Uncertainty Principle (61 questions, 24%), and Bohr's model (36 questions, 14%) have been asked the most. Quantum mechanical model has also led over the last five years, with 39 questions. Dual Behaviour of Matter and Heisenberg Uncertainty Principle has produced the most tough questions (8).

  1. 1Consider two radiations of wavelengths 1. Å 2. Å The ratio of the energies of these two radiations is ________ (Nearest integer).08 Apr, 2026 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  2. 2If shortest wavelength of hydrogen atom in Lyman series is , then longest wavelength in Balmer series of is:06 Apr, 2026 (M)Hydrogen spectrum
  3. 3Match the LIST-I with LIST-II List-I Orbital List-II Radial nodes and nodal plane A. I. Radial node + two nodal planes B. II. Radial node + 06 Apr, 2026 (M)Quantum mechanical model
  4. 4The Bohr radius of a hydrogen like species is pm. The species and the stationary state are respectively (Given : Hydrogen atom Bohr radius i06 Apr, 2026 (E)Bohr's model
  5. 5Arrange the following atomic orbitals of multi electron atoms in order of increasing energy. A. B. C. D. E. Choose the correct answer from t05 Apr, 2026 (M)Quantum mechanical model
  6. 6Identify the correct statements from the following: A. Heisenberg uncertainty principle is applicable to electrons. B. The size of orbital i05 Apr, 2026 (M)Electronic configuration
  7. 7Which of the following statement(s) is/are true ? A. If two orbitals have the same value of , the orbital with lower value of will have lowe05 Apr, 2026 (E)Quantum mechanical model
  8. 8What is the ratio of wave number of first line (lowest energy line) of Balmer series of H atomic spectrum to first line of its Brackett seri04 Apr, 2026 (M)Hydrogen spectrum
  9. 9Which of the following is correct set of quantum numbers of electron in Chromium (Atomic number ) in accordance with Aufbau principle?04 Apr, 2026 (M)Quantum mechanical model
  10. 10A monoatomic anion has neutrons and electrons. Atomic mass, group in the periodic table and physical state at room temperature of the elemen04 Apr, 2026 (M)Atomic Mass and Atomic Size
  11. 11The species having identical radii according to the Bohr's theory are: A. (first orbit) B. (first orbit) C. (Second orbit) D. (first orbit) 04 Apr, 2026 (E)Bohr's model
  12. 12What is the energy (in J atom ) required for the following process? (Take the ionization energy for the H atom in the ground state as J atom02 Apr, 2026 (M)Bohr's model
  13. 13The surface of sodium metal is irradiated with radiation of wavelength nm. The kinetic energy of ejected electrons is J. The work function o02 Apr, 2026 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  14. 14The wave numbers of three spectral lines of H atom are considered. Identify the set of spectral lines belonging to Balmer series. ( Rydberg 28 Jan, 2026 (M)Hydrogen spectrum
  15. 15Which of the following point in Figure 2 most accurately represents the nodal surface as shown in Figure 1?28 Jan, 2026 (M)Quantum mechanical model
  16. 16The wavelength of photon ' A ' is 400 nm. The frequency of photon ' B ' is . The wave number of photon ' is . The correct order of energy of28 Jan, 2026 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  17. 17Two positively charged particles and have been accelerated across the same potential difference of 200 keV as shown below. [Given mass of am28 Jan, 2026 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  18. 18The hydrogen spectrum consists of several spectral lines in Lyman series ( , has lowest energy among Lyman series). Similarly it consists of24 Jan, 2026 (M)Hydrogen spectrum
  19. 19The wavelength of spectral line obtained in the spectrum of ion, when the transition takes place between two levels whose sum is 4 and diffe24 Jan, 2026 (E)Hydrogen spectrum
  20. 20Given, (A) (B) The maximum number of electron(s) in an atom that can have the quantum numbers as given in (A) and (B) respectively are :23 Jan, 2026 (M)Quantum mechanical model
  21. 21Which of the following statements regarding the energy of the stationary state is true in the following one - electron systems ?23 Jan, 2026 (M)Bohr's model
  22. 22The work functions of two metals and are in the ratio. When these metals are exposed to photons of energy 6 eV, the kinetic energy of libera23 Jan, 2026 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  23. 23Identify the INCORRECT statements from the following: A. Notation represents 24 protons and 12 neutrons. B. Wavelength of a radiation of fre23 Jan, 2026 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  24. 24The energy required by electrons, present in the first Bohr orbit of hydrogen atom to be excited to second Bohr orbit is . Given: .22 Jan, 2026 (M)Bohr's model
  25. 25The energy of first (lowest) Balmer line of H atom is . The energy (in J) of second Balmer line of H atom is :22 Jan, 2026 (E)Hydrogen spectrum
  26. 26Given below are two statements : Statement I : When an electric discharge is passed through gaseous hydrogen, the hydrogen molecules dissoci21 Jan, 2026 (M)Hydrogen spectrum
  27. 27Consider the following spectral lines for atomic hydrogen : A. First line of Paschen series B. Second line of Balmer series C. Third line of21 Jan, 2026 (E)Hydrogen spectrum
  28. 28The energy of an electron in first Bohr orbit of H -atom is -13.6 eV. The magnitude of energy value of electron in the first excited state o08 Apr, 2025 (E)Bohr's model
  29. 29Correct statements for an element with atomic number 9 are A. There can be 5 electrons for which and 4 electrons for which B. There is only 08 Apr, 2025 (E)Quantum mechanical model
  30. 30Which of the following statements are correct, if the threshold frequency of caesium is ? A. When Cs is placed inside a vacuum chamber with 07 Apr, 2025 (M)Hydrogen spectrum
  31. 31The extra stability of half-filled subshell is due to (A) Symmetrical distribution of electrons (B) Smaller coulombic repulsion energy (C) T07 Apr, 2025 (E)Electronic configuration
  32. 32Which one of the following about an electron occupying the 1 s orbital in a hydrogen atom is incorrect ? (Bohr's radius is represented by a 04 Apr, 2025 (M)Quantum mechanical model
  33. 33Consider the ground state of chromium atom . How many electrons are with Azimuthal quantum number and respectively ?04 Apr, 2025 (E)Quantum mechanical model
  34. 34Which of the following postulate of Bohr's model of hydrogen atom in not in agreement with quantum mechanical model of an atom ?03 Apr, 2025 (M)Quantum mechanical model
  35. 35For electron in ' 2 s ' and ' 2 p ' orbitals, the orbital angular momentum values, respectively are :03 Apr, 2025 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  36. 36According to Bohr's model of hydrogen atom, which of the following statement is incorrect?02 Apr, 2025 (M)Bohr's model
  37. 37Which of the following statements are true? (A) The subsidiary quantum number describes the shape of the orbital occupied by the electron. (02 Apr, 2025 (E)Quantum mechanical model
  38. 38Given below are two statements : Statement (\( {I}\)): The radii of isoelectronic species increases in the order. \( {Mg}^{2+} {Na}^{+} {F}^29 Jan, 2025 (M)Atomic Mass and Atomic Size
  39. 39If \( {a}_0\) is denoted as the Bohr radius of hydrogen atom, then what is the de-Broglie wavelength \(( )\) of the electron present in the 29 Jan, 2025 (M)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  40. 40For hydrogen like species, which of the following graphs provides the most appropriate representation of E vs Z plot for a constant n ? [E: 29 Jan, 2025 (E)Bohr's model
  41. 41The calculated spin-only magnetic moments of and respectively are :29 Jan, 2025 (E)Quantum mechanical model
  42. 42Given below are two statements : Statement (I) : It is impossible to specify simultaneously with arbitrary precision, both the linear moment29 Jan, 2025 (E)Dual Behaviour of Matter and Heisenberg Uncertainty Principle
  43. 43In a multielectron atom, which of the following orbitals described by three quantum numbers will have same energy in absence of electric and28 Jan, 2025 (M)Quantum mechanical model
  44. 44Which of the following is/are not correct with respect to energy of atomic orbitals of hydrogen atom? (A) (B) (C) (D) Choose the correct ans28 Jan, 2025 (E)Electronic configuration
  45. 45For hydrogen atom, the orbital/s with lowest energy is/are : (A) 4 s (B) (C) (D) (E) Choose the correct answer from the options given below 24 Jan, 2025 (E)Quantum mechanical model
  46. 46Heat treatment of muscular pain involves radiation of wavelength of about 900 nm . Which spectral line of H atom is suitable for this? Given23 Jan, 2025 (M)Hydrogen spectrum
  47. 47Given below are two statements : Statement (I) : For a given shell, the total number of allowed orbitals is given by . Statement (II) : For 23 Jan, 2025 (E)Quantum mechanical model
  48. 48Given below are two statements about X-ray spectra of elements : Statement (I) : A plot of ( frequency of -rays emitted) vs atomic mass is a23 Jan, 2025 (E)Atomic Models
  49. 49Radius of the first excited state of Helium ion is given as : radius of first stationary state of hydrogen atom.22 Jan, 2025 (M)Bohr's model
  50. 50Given below are two statements : Statement (I) : A spectral line will be observed for a transition. Statement (II) : and are degenerate orbi22 Jan, 2025 (E)Electronic configuration

Frequently Asked Questions

1.How many questions are available for Structure of Atom?

This chapter includes 251 questions compiled from JEE Main papers spanning 2002 to 2026.

2.Are these questions only from JEE Main, or from other exams too?

These are JEE Main questions specifically for the Structure of Atom chapter. Questions from other exams like NTA Abhyas (JEE Main) or JEE Advanced are organised separately under their respective exam sections.

3.Is Structure of Atom an important chapter for JEE Main Chemistry?

Structure of Atom has appeared in 25 of the 25 years of JEE Main papers covered here, with 251 questions across 192 papers - about one per paper it appears in.

4.What is the difficulty level of Structure of Atom questions in JEE Main?

Of the 252 questions analysed for this chapter, 46% are easy, 46% moderate and 8% tough. 2023 had the most, with 29 questions.

5.Which topics in Structure of Atom should I focus on?

These topics have carried the most weightage in Structure of Atom:

  • Quantum mechanical model - 72 questions (29%)
  • Dual Behaviour of Matter and Heisenberg Uncertainty Principle - 61 questions (24%)
  • Bohr's model - 36 questions (14%)
  • Dual Behaviour of Matter and Heisenberg Uncertainty Principle has produced the most tough questions (8).
6.Is Structure of Atom's weightage in JEE Main going up or down?

Across all 192 papers analysed, Structure of Atom has averaged about 1.3 questions per paper. In the last three years (2024–2026), that average has stayed about the same, at about 1.3 questions per paper. Use the year-wise numbers on this page for the exact trend before you decide how much time to give it.