Atomic Structure JEE Main Questions with Solutions PDF & Answers

IIT JEE Atomic Structure Last 10 Years' Most Asked Topics

Atomic structure JEE Main questions asked in the last 10 years included questions from different atomic structure topics. The table below shows the topics that were asked most often from this chapter.

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JEE Main 2026 Atomic Structure Most Asked Concepts

Refer to the table given below for Atomic Structure PYQ JEE Main most asked concepts in 2026. In JEE Main, questions were asked from different topics.

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Types of Questions Asked in JEE Main from Atomic Structure

Different types of atomic structure JEE Main questions were asked from this chapter. Refer to the types of Atomic Structure JEE questions given below:

1. Questions based on the calculation of energy, wavelength, and frequency.

2. Questions on the Bohr model and the hydrogen spectrum

3. Questions on quantum numbers and electronic configuration

4. Questions on de Broglie wavelength and the Heisenberg Uncertainty Principle

Difficulty Level of Atomic Structure JEE Advanced Questions

JEE Main questions on atomic structure were direct, formula-based, and easy, while Atomic Structure JEE Advanced questions were more conceptual and multi-concept type questions:

Also Check: JEE Main 2027 Important Formulas

IIT JEE Atomic Structure Previous Year Questions

Practising Atomic Structure JEE Main PYQ is one of the best ways to prepare for IIT JEE. The questions below will help you get a feel for the exam pattern, the key topics, and also the general level of difficulty they are asking in Atomic Structure.

Question 1: Consider two radiations of wavelengths :

1. $\lambda_1=2000$
2. $\lambda_2=6000$

The ratio of the energies of these two radiations $\left(\frac{E_1}{E_2}\right)$ is $\_\_\_\_$ . (Nearest integer)

(1) 3

(2) 4

(3) 2

(4) 1

Solution: Option (1)

$\begin{aligned}
& \mathrm{E}_{\text {photon }}=\frac{\mathrm{hc}}{\lambda} \\
& \Rightarrow \frac{\mathrm{E}_1}{\mathrm{E}_2}=\frac{\lambda_2}{\lambda_1} \\
& \Rightarrow \frac{\mathrm{E}_1}{\mathrm{E}_2}=\frac{6000}{2000} \\
& \Rightarrow \frac{\mathrm{E}_1}{\mathrm{E}_2}=3
\end{aligned}$

Question 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) $\mathrm{Li}^{2+}, 3$

(2) $\mathrm{He}^{+}, 3$

(3) $\mathrm{He}^{+}, 2$

(4) $\mathrm{Li}^{2+}, 2$

Solution: Option (4)

$\begin{aligned}
& \mathrm{r}_{\text {species }}=\mathrm{a}_0 \frac{\mathrm{n}^2}{\mathrm{Z}} \\
& 70.53=52.9\left(\frac{\mathrm{n}^2}{\mathrm{Z}}\right) \\
& \frac{\mathrm{n}^2}{\mathrm{Z}}=\frac{70.53}{52.9}=1.33=\frac{4}{3}
\end{aligned}$

Data will satisfy if $\mathrm{n}=2$ and $\mathrm{z}=3$

$\mathrm{Li}^{+2}, 2 \Rightarrow \frac{4}{3}=1.33$

Question 3: If shortest wavelength of hydrogen atom in Lyman series is x , then longest wavelength in Balmer series of $\mathrm{He}^{+}$is :

(1) $\frac{9 x}{5}$

(2) $\frac{36 x}{5}$

(3) $\frac{x}{4}$

(4) $\frac{5 x}{9}$

Solution: Option (1)

$\frac{1}{\mathrm{x}}=\mathrm{R} \times 1^2 \times\left(\frac{1}{1^2}-\frac{1}{\infty^2}\right)$ (1)

$\frac{1}{\lambda}=\mathrm{R} \times 2^2 \times\left(\frac{1}{2^2}-\frac{1}{3^2}\right)$ (2)

$\begin{aligned} & \frac{\mathrm{x}}{\lambda}=\mathrm{R} \times 4 \times \frac{5}{4 \times 9} \\ & \frac{1}{\lambda}=\frac{1}{\mathrm{x}} \times \frac{5}{9} \\ & \lambda=\frac{9 \mathrm{x}}{5}\end{aligned}$

Question 4: Which of the following statement(s) is/are true ?
(A) If two orbitals have the same value of ( $\mathrm{n}+l$ ), the orbital with lower value of n will have lower energy.
(B) Energies of the orbitals in the same subshell increase with increase in atomic number.
(C) The size of $2 p_x$ orbital is less than the size of $3 \mathrm{p}_{\mathrm{x}}$ orbital.
(D) Among 5f,6s, 4d, 5p and 5d orbitals, none of the orbitals have 2 radial nodes.

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

Solution: Option (2)

(a) If two orbitals are having same value of " $n+\ell$ " then the orbital having lower value of ' $n$ ' will have lower energy.
(b) Energies of the orbitals in the same subshell decreases with increase in atomic number.
(c) Size of $2 p_x<3 p_x$

Question 5: The wavelength of photon ' $A$ ' is 400 nm. The frequency of photon ' $B$ ' is $10^{16} s^{-1}$. The wave number of photon ' $C$ ' is $10^4 \mathrm{~cm}^{-1}$. The correct order of energy of these photons is:

(1) $A>C>B$

(2) $A>B>C$

(3) $C>B>A$

(4) $B>A>C$

Solution: Option (4)

(1) Wavelength of A=400 nm.

(2)$\begin{aligned}
& v=\frac{C}{\lambda} \Rightarrow \text { wavelength of } \mathrm{B}(\lambda)=\frac{3 \times 10^8}{10^{16}} \\
& =3 \times 10^{-5}=30 \times 10^{-9}=30 \mathrm{~nm}
\end{aligned}$

(3)> Wavelength of $C(\lambda)=\frac{1}{\bar{v}}=\frac{1}{10^4}=10^{-4} \mathrm{~cm}$ $=10^{-6} \mathrm{~m}=1000 \mathrm{~nm}$

Here $\lambda_{\mathrm{C}}>\lambda_{\mathrm{A}}>\lambda_{\mathrm{B}}$
$\mathrm{E} \propto \frac{1}{\lambda}$
So $\mathrm{E}_{\mathrm{c}}<\mathrm{E}_{\mathrm{A}}<\mathrm{E}_{\mathrm{B}}$

Question 6: The wave numbers of three spectral lines of the H atom are considered. Identify the set of spectral lines belonging to the Balmer series.

( $\mathrm{R}=$ Rydberg constant)

(1) $\frac{3 R}{4}, \frac{3 R}{16}, \frac{7 R}{144}$

(2) $\frac{7 R}{144}, \frac{3 R}{16}, \frac{16 R}{255}$

(3) $\frac{5 R}{36}, \frac{8 R}{9}, \frac{15 R}{16}$

(4) $\frac{5 R}{36}, \frac{3 R}{16}, \frac{21 R}{100}$

Solution: Option (4)

For Balmer series $\mathrm{n}_{\mathrm{i}}($ or $) \mathrm{n}_{\mathrm{f}}=2$
For the absorption spectrum of the H atom

$\begin{array}{lll}
\mathrm{n}_{\mathrm{i}} & \mathrm{n}_{\mathrm{f}} \\
2 & 3 & \bar{v}=R\left[\frac{1}{2^2}-\frac{1}{3^2}\right]=\frac{5 R}{36} \\
2 & 4 & \bar{v}=R\left[\frac{1}{2^2}-\frac{1}{4^2}\right]=\frac{3 R}{16} \\
2 & 5 & \bar{v}=R\left[\frac{1}{2^2}-\frac{1}{5^2}\right]=\frac{21 R}{100} \\
\end{array}$

Question 7: The hydrogen spectrum consists of several spectral lines in Lyman series $\left(\mathrm{L}_1, \mathrm{~L}_2, \mathrm{~L}_3 \ldots \ldots\right.$; $\mathrm{L}_1$ has lowest energy among Lyman series). Similarly it consists of several spectral lines in Balmer series ( $\mathrm{B}_1, \mathrm{~B}_2, \mathrm{~B}_3 \ldots ; \mathrm{B}_1$ has lowest energy among Balmer lines). The energy of $\mathrm{L}_1$ is x times the energy of $\mathrm{B}_1$. The value of $x$ is $\ldots \times 10^{-1}$ (Nearest integer)

(1) 54

(2) 56

(3) 35

(4) 67

Solution: Option (1)

$\begin{aligned} & \Delta E_L=13.6 \times Z^2\left[\frac{1}{1^2}-\frac{1}{2^2}\right]=13.6 \times Z^2 \times \frac{3}{4} \\ & \Delta E_B=13.6 \times Z^2\left[\frac{1}{2^2}-\frac{1}{3^2}\right]=13.6 \times Z^2 \times \frac{5}{4 \times 9} \\ & \frac{\Delta E_L}{\Delta E_B}=\frac{3}{5} \times 9=\frac{27}{5}=5.4=54 \times 10^{-1} \\ & \therefore x=54\end{aligned}$

Question 8: The wavelength of spectral line obtained in the spectrum of $\mathrm{Li}^{2+}$ ion, when the transition takes place between two levels whose sum is 4 and difference is 2 , is

(1) $2.28 \times 10^6 \mathrm{~cm}$

(2) $1.14 \times 10^{-7} \mathrm{~cm}$

(3) $1.14 \times 10^{-6} \mathrm{~cm}$

(4) $2.28 \times 10^{-7} \mathrm{~cm}$

Solution: Option (3)

$\begin{aligned} & n_2+n_1=4 \\ & n_2-n_1=2\end{aligned}$

$\begin{aligned} & 2 n_2=6 \\ & n_2=3 \\ & n_1=1 \\ & \frac{1}{\lambda}=R_H \times z^2\left(\frac{1}{1}-\frac{1}{9}\right) \\ & \frac{1}{\lambda}=10^7 \times 9\left(\frac{8}{9}\right) \\ & \lambda=\frac{1}{8} \times 10^{-7}=1.25 \times 10^{-8} \mathrm{~A}=1.25 \times 10^{-6} \mathrm{~cm}\end{aligned}$

Question 9: The work functions of two metals ( $\mathrm{M}_{\mathrm{A}}$ and $\mathrm{M}_{\mathrm{B}}$ ) are in the $1: 2$ ratio. When these metals are exposed to photons of energy 6 eV , the kinetic energy of liberated electrons of $M_A: M_B$ is in the ratio of 2.642:1. The work function (in eV ) of $\mathrm{M}_{\mathrm{A}}$ and $\mathrm{M}_{\mathrm{B}}$ are respectively.

(1) $1.5,3.0$

(2) $2.3,4.6$

(3) $3.1,6.2$

(4) $1.4,2.8$

Solution: Option (2)

$\begin{aligned} & E=\phi+K \cdot E \\ & K \cdot E_B=6-\phi_B \\ & \frac{K \cdot E_A}{K \cdot E_B}=\frac{6-\phi_A}{6-\phi_B} \quad \phi_B=2 \phi A \\ & \frac{2 \cdot 642}{1}=\frac{6-\phi_1}{6-2 \phi_1} \\ & \phi_1=2.3 \\ & \phi_2=4.6\end{aligned}$

Question 10: Identify the INCORRECT statements from the following:

A.Notation ${ }_{12}^{24} \mathrm{Mg}$ represents 24 protons and 12 neutrons.

B. Wavelength of a radiation of frequency $4.5 \times 10^{15} \mathrm{~S}^{-1}$ is $6.7 \times 10^{-8} \mathrm{~m}$.

C. One radiation has wavelength $=\lambda_1(900 \mathrm{~nm})$ and energy $=E_1$. Other radiation has wavelength $=\lambda_2(300 \mathrm{~nm})$ and energy $=E_2 \cdot E_1: E_2=3: 1$.

D. Number of photons of light of wavelength 2000 pm that provides 1 J of energy is $1.006 \times 10^{16}$.

Choose the correct answer from the options given below:

(1) $A$ and $C$ Only

(2) $A$ and B Only

(3) $A$ and D Only

(4) $B$ and $C$ Only

Solution: Option (1)

$\begin{aligned} & E=\frac{h c}{\lambda} \\ & v=\frac{c}{\lambda} \\ & \frac{E_1}{E_2}=\frac{\lambda_2}{\lambda_1}\end{aligned}$

Question 11: 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) $x^2$

(2) $\frac{x}{1.35}$

(3) $1.35 x$

(4) $2 x$

Solution: Option (3)

First line of Balmer $\quad \Delta E_1=R H h c\left[\frac{1}{2^2}-\frac{1}{3^2}\right]=R H h c\left[\frac{5}{36}\right]$

Second line of Balmer $\Delta E_2=R H h c\left[\frac{1}{2^2}-\frac{1}{4^2}\right]=R H h c\left[\frac{3}{16}\right]$

$\frac{\Delta E_2}{\Delta E_1}=\frac{\frac{3}{11}}{\frac{5}{36}}=\frac{3 \times 36}{16 \times 5}=\frac{108}{80}=\frac{27}{20}$

The energy of $2^{\text {nd }}$ line $=\frac{27}{20} x=1.35 x$

Question 12: The energy required by electrons, present in the first Bohr orbit of hydrogen atom to be excited to second Bohr orbit is $\_\_\_\_$ $\mathrm{J} \mathrm{mol}^{-1}$

Given: $\mathrm{R}_{\mathrm{H}}=2.18 \times 10^{-11} \mathrm{ergs}$

(1) $9.835 \times 10^5$

(2) $9.835 \times 10^{12}$

(3) $1.635 \times 10^{-11}$

(4) $1.635 \times 10^{-18}$

Solution: Option (1)

$\quad E_2-E_1=R_H\left[\frac{1}{N_1^2}-\frac{1}{N_2^2}\right] \times 6 \times 10^{23}=2.18 \times 10^{-18}\left[\frac{3}{4}\right] \times 6 \times 10^{23}=9.81 \times 10^5 \mathrm{~J} / \mathrm{mol}$

Question 13: Statement – I: When an electric discharge is passed through gaseous hydrogen, the hydrogen molecules dissociate and the energetically excited hydrogen atoms produce electromagnetic radiation of discrete frequencies.

Statement – II: The frequency of second line Balmer series obtained from He equal to that of first line of Lyman series obtained from hydrogen atom. In the light of the above statements, Choose the correct answer from the options given below:

(1) Both statement I and statement II are false

(2) Both statement I and statement II are true

(3) Statement I is true but statement II is false

(4) Statement I is false but statement II is true

Solution: Option (2)

Sol: $1^{\text {st }}$ line of Hyddrogen atom in Lymen series,

Second line of $\mathrm{He}^{+}$ion in Balmar series,
Third line of $\mathrm{Li}^{+2}$ ion in Paschen series Above are having same frequency.

Question 14: Consider the following spectral lines for atomic hydrogen:

A) First line of Paschen series
B) Second line of Balmer series
C) Third line of Paschen series
D) Fourth line of Bracket series

The correct arrangement of the above lines in ascending order of energy is:

(1) $D<A<C<B$

(2) $C<D<B<A$

(3) $A<B<C<D$

(4) $D<C<A<B$

Solution: Option (1)

$\Delta E=13.6 Z^2\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$

Question 15: One H atom, One $\mathrm{He}^{+}$ion and one $\mathrm{Li}^{2+}$ ion taken. Electrons in all the atom & ions are present in $4^{\text {th }}$ Excited state. What is the maximum number of spectral lines obtained?

(1) 12

(2) 10

(3) 30

(4) 29

Solution: Option (1)

4 spectral lines each form $H$, $\mathrm{He}^{+}$and $\mathrm{Li}^{2+}$.

$
4+4+4=12
$

Best Books for JEE Main Questions on Atomic Structure

While preparing for IIT JEE, it is very important to follow the best books because they help properly cover all the concepts. Refer to the books given below for solving IIT JEE Main and atomic structure JEE Advanced questions.