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Structure of Atom

Previous year questions with solutions · 2025 – 2026

39Questions
31Papers covered
5.47% ↑26.3%Weightage in 2026
’25
’26
Year-wise statistics questions · papers · average per paper · weightage
YearQuestionsPapersAvg / paperWeightage
202626191.45.47% ↑26.3%
202513121.14.33%

33 questions · newest paper first · page 1 of 2

1

If shortest wavelength of hydrogen atom in Lyman series is x, then longest wavelength in Balmer series of He+ is:

  1. 9x5
  2. 36x5
  3. x4
  4. 5x9
JEE Main 2026 (Online) 6th April Morning Shift
2

The Bohr radius of a hydrogen like species is 70.53 pm. The species and the stationary state (n) are respectively (Given : Hydrogen atom Bohr radius is 52.9 pm)

  1. Li2+, 3
  2. He+, 3
  3. He+, 2
  4. Li2+, 2
JEE Main 2026 (Online) 6th April Evening Shift
3

Arrange the following atomic orbitals of multi electron atoms in order of increasing energy. Choose the correct answer from the options given below:

  1. C < D < B < A < E
  2. B < A < E < C < D
  3. E < C < D < B < A
  4. E < B < A < D < C
JEE Main 2026 (Online) 5th April Morning Shift
4

Identify the correct statements from the following : Choose the correct answer from the options given below:

  1. A, B and C Only
  2. A, B and D Only
  3. B, C and D Only
  4. A, C and D Only
JEE Main 2026 (Online) 5th April Morning Shift
5

Which of the following statement(s) is/are true ? Choose the correct answer from the options given below :

  1. A, B and C only
  2. A and C only
  3. C and D only
  4. A only
JEE Main 2026 (Online) 5th April Evening Shift
6

What 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 series?

  1. 5 : 1
  2. 5 : 0.81
  3. 5 : 1.75
  4. 5 : 27
JEE Main 2026 (Online) 4th April Morning Shift
7

Which of the following is correct set of 4 quantum numbers of 19th electron in Chromium (Atomic number = 24) in accordance with Aufbau principle?

  1. n = 3, l = 2, m = +2, s = + 12
  2. n = 3, l = 2, m = -2, s = + 12
  3. n = 4, l = 1, m = 0, s = + 12
  4. n = 4, l = 0, m = 0, s = + 12
JEE Main 2026 (Online) 4th April Morning Shift
8

The species having identical radii according to the Bohr's theory are : Choose the correct answer from the options given below :

  1. A and C Only
  2. A and E Only
  3. B and E Only
  4. C and D Only
JEE Main 2026 (Online) 4th April Evening Shift
9

What is the energy (in J atom-1) required for the following process ? Li2+(g) Li3+(g) + e- (Take the ionization energy for the H atom in the ground state as 2.18 10-18 J atom-1)

  1. 8.72 10-18
  2. 1.962 10-18
  3. 1.962 10-17
  4. 6.54 10-17
JEE Main 2026 (Online) 2nd April Morning Shift
10

The wave numbers of three spectral lines of H atom are considered. Identify the set of spectral lines belonging to Balmer series. (R = Rydberg constant)

  1. 5R36, 3R16, 21R100
  2. 7R144, 3R16, 16R255
  3. 3R4, 3R16, 7R144
  4. 5R36, 8R9, 15R16
JEE Main 2026 (Online) 28th January Morning Shift
11

[figure] Figure 1. electron probability density for 2s orbital [figure] Figure 2. wave function for 2s orbital Which of the following point in Figure 2 most accurately represents the nodal surface as shown in Figure 1?

  1. D
  2. B
  3. C
  4. A
JEE Main 2026 (Online) 28th January Morning Shift
12

The wavelength of photon 'A' is 400 nm. The frequency of photon 'B' is 1016 s-1. The wave number of photon 'C' is 104 cm-1. The correct order of energy of these photons is :

  1. A > C > B
  2. C > B > A
  3. B > A > C
  4. A > B > C
JEE Main 2026 (Online) 28th January Evening Shift
13

The wavelength of spectral line obtained in the spectrum of Li2+ ion, when the transition takes place between two levels whose sum is 4 and difference is 2, is

  1. 1.14 10-6 cm
  2. 2.28 10-6 cm
  3. 1.14 10-7 cm
  4. 2.28 10-7 cm
JEE Main 2026 (Online) 24th January Evening Shift
14

Given, (A) n = 5, ml = -1 (B) n = 3, l = 2, ml = -1, ms = + 12 The maximum number of electron(s) in an atom that can have the quantum numbers as given in (A) and (B) respectively are :

  1. 4 and 1
  2. 2 and 4
  3. 26 and 1
  4. 8 and 1
JEE Main 2026 (Online) 23rd January Morning Shift
15

Which of the following statements regarding the energy of the stationary state is true in the following one-electron systems ?

  1. +2.18 10-18 J for second orbit of He+ ion
  2. +8.72 10-18 J for first orbit of He+ ion
  3. -1.09 10-18 J for second orbit of H atom.
  4. -2.18 10-18 J for third orbit of Li2+ ion
JEE Main 2026 (Online) 23rd January Morning Shift
16

The work functions of two metals (MA and MB) are in the 1 : 2 ratio. When these metals are exposed to photons of energy 6 eV, the kinetic energy of liberated electrons of MA : MB is in the ratio of 2.642 : 1. The work functions (in eV) of MA and MB are respectively.

  1. 3.1, 6.2
  2. 1.5, 3.0
  3. 2.3, 4.6
  4. 1.4, 2.8
JEE Main 2026 (Online) 23rd January Evening Shift
17

Identify the INCORRECT statements from the following : Choose the correct answer from the options given below :

  1. A and D Only
  2. A and C Only
  3. A and B Only
  4. B and C Only
JEE Main 2026 (Online) 23rd January Evening Shift
18

The energy required by electrons, present in the first Bohr orbit of hydrogen atom to be excited to second Bohr orbit is J mol-1. Given: RH = 2.18 10-11 ergs.

  1. 9.835 1012
  2. 1.635 10-11
  3. 1.635 10-18
  4. 9.835 105
JEE Main 2026 (Online) 22nd January Morning Shift
19

The energy of first (lowest) Balmer line of H atom is x J. The energy (in J) of second Balmer line of H atom is :

  1. x1.35
  2. 1.35x
  3. x2
  4. 2x
JEE Main 2026 (Online) 22nd January Evening Shift
20

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are true
  2. Statement I is true but Statement II is false
  3. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are false
JEE Main 2026 (Online) 21st January Morning Shift
21

Consider the following spectral lines for atomic hydrogen : The correct arrangement of the above lines in ascending order of energy is :

  1. D < C < A < B
  2. A < B < C < D
  3. D < A < C < B
  4. C < D < B < A
JEE Main 2026 (Online) 21st January Evening Shift
22

Correct statements for an element with atomic number 9 are: Choose the correct answer from the options given below:

  1. A and B Only
  2. A, C and D Only
  3. A and C Only
  4. C and D Only
JEE Main 2025 (Online) 8th April Evening Shift
23

[figure] Which of the following statements are correct, if the threshold frequency of caesium is 5.16 1014 Hz? Choose the correct answer from the options given below:

  1. B, C and D Only
  2. A, C, D and E Only
  3. A, B, D and E Only
  4. A, D and E Only
JEE Main 2025 (Online) 7th April Morning Shift
24

The extra stability of half-filled subshell is due to : Identify the correct statements :

  1. B, D and E only
  2. A, B, D and E only
  3. B, C and D only
  4. A, B and D only
JEE Main 2025 (Online) 7th April Evening Shift
25

Which one of the following about an electron occupying the 1s orbital in a hydrogen atom is incorrect? (Bohr's radius is represented by a0)

  1. The probability density of finding the electron is maximum at the nucleus
  2. The total energy of the electron is maximum when it is at a distance a0 from the nucleus
  3. The electron can be found at a distance 2a0 from the nucleus
  4. The 1s orbital is spherically symmetrical
JEE Main 2025 (Online) 4th April Morning Shift
26

Consider the ground state of chromium atom (Z = 24). How many electrons are with Azimuthal quantum number l = 1 and l = 2 respectively ?

  1. 16 and 5
  2. 12 and 5
  3. 12 and 4
  4. 16 and 4
JEE Main 2025 (Online) 4th April Evening Shift
27

Which of the following postulate of Bohr's model of hydrogen atom is not in agreement with quantum mechanical model of an atom?

  1. The electron in a H atom's stationary state moves in a circle around the nucleus.
  2. An atom can take only certain distinct energies E1, E2, E3, etc. These allowed states of constant energy are called the stationary states of atom.
  3. An atom in a stationary state does not emit electromagnetic radiation as long as it stays in the same state.
  4. When an electron makes a transition from a higher energy stationary state to a lower energy stationary state, then it emits a photon of light.
JEE Main 2025 (Online) 3rd April Morning Shift
28

For electrons in '2s' and '2p' orbitals, the orbital angular momentum values, respectively are:

  1. 0 and 6 h2
  2. 0 and 2 h2
  3. 2 h2 and 0
  4. h2 and 2 h2
JEE Main 2025 (Online) 3rd April Evening Shift
29

According to Bohr's model of hydrogen atom, which of the following statement is incorrect?

  1. Radius of 4th orbit is four times larger than that of 2nd orbit
  2. Radius of 8th orbit is four times larger than that of 4th orbit
  3. Radius of 6th orbit is three times larger than that of 4th orbit
  4. Radius of 3rd orbit is nine times larger than that of 1st orbit
JEE Main 2025 (Online) 2nd April Morning Shift
30

Which of the following statements are true? Choose the correct answer from the options given below:

  1. (A) and (B) only
  2. (B) and (D) only
  3. (C) and (D) only
  4. (A), (B) and (C) only
JEE Main 2025 (Online) 2nd April Evening Shift