Atoms

11 JEE Main questions · Physics

Atomic models

PhysicsJEE Main 21 Jan 2026, Shift 1·Q13·MCQ·Easy–moderate
Open
If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is m. (Atomic number of gold $= 79$ and $\dfrac{1}{4\pi\epsilon_0} = 9\times10^{9}$ in SI units)
1. (1) $2.95\times10^{-14}$
2. (2) $2.95\times10^{-16}$
3. (3) $3.85\times10^{-16}$
4. (4) $3.85\times10^{-14}$
PhysicsJEE Main 22 Jan 2026, Shift 1·Q2·MCQ·Easy–moderate
Open
7.9 MeV $\alpha$ –particle scatters from a target material of atomic number 79. From the given data the estimated diameter of nuclei of the target material is (approximately) m. $\left[\dfrac{1}{4\pi\epsilon_0} = 9\times10^{9}\ \mathrm{Nm^2/C^2}\ \text{and electron charge} = 1.6\times10^{-19}\ \mathrm{C}\right]$
1. (1) $5.76\times10^{-14}$
2. (2) $1.44\times10^{-13}$
3. (3) $2.88\times10^{-14}$
4. (4) $1.69\times10^{-12}$
PhysicsJEE Main 22 Jan 2026, Shift 2·Q7·MCQ·Easy–moderate
Open
The smallest wavelength of Lyman series is 91 nm. The difference between the largest wavelengths of Paschen and Balmer series is nearly nm.
1. (1)1875
2. (2)1550
3. (3)1217
4. (4)1784

PhysicsJEE Main 23 Jan 2026, Shift 1·Q13·MCQ·Easy–moderate

In hydrogen atom spectrum, (

R \rightarrow

Rydberg's constant)

A.	the maximum wavelength of the radiation of Lyman series is $\dfrac{4}{3R}$
B.	the Balmer series lies in the visible region of the spectrum
C.	the minimum wavelength of the radiation of Paschen series is $\dfrac{9}{R}$
D.	the minimum wavelength of Lyman series is $\dfrac{5}{4R}$

Choose the correct answer from the options given below:

(1)B, D Only
(2)A, B and C Only
(3)A, B and D Only
(4)A, B Only

PhysicsJEE Main 4 Apr 2026, Shift 2·Q18·MCQ·Easy
Open
In Rutherford's alpha-particle scattering experiment, only a few alpha particles rebound back because
(A) The size of gold nucleus is very small as compared to the size of gold atom.
(B) Alpha particle and gold nucleus have equal charge.
(C) The impact parameter is minimum for a few alpha particles.
(D) A few alpha particles have very high kinetic energy.
(E) Only a few alpha particles undergo head-on collision with the nuclei.
Choose the correct answer from the options given below:
1. (1)A, B Only
2. (2)B, E Only
3. (3)C, D Only
4. (4)A, C, E Only
PhysicsJEE Main 6 Apr 2026, Shift 1·Q19·MCQ·Easy–moderate
Open
The ratio of momentum of the photons of the $1^{\text{st}}$ and $2^{\text{nd}}$ line of Balmer series of Hydrogen atoms is $\alpha/\beta$ . The possible values of $\alpha$ and $\beta$ are :-
1. (1)27 and 20
2. (2)3 and 16
3. (3)5 and 36
4. (4)20 and 27

Bohr model

PhysicsJEE Main 21 Jan 2026, Shift 2·Q16·MCQ·Easy–moderate
Open
The energy of an electron in an orbit of the Bohr's atom is $0.04E_0$ where $E_0$ is the ground state energy. If L is the angular momentum of the electron in this orbit and h is the Planck's constant, then $\dfrac{2\pi L}{h}$ is :
1. (1)2
2. (2)4
3. (3)5
4. (4)6
We corrected a printing error in the original paper
Source printed “ $-0.04E_0$ eV” (positive, i.e. unbound, since $E_0$ is negative; and a doubled unit).
PhysicsJEE Main 24 Jan 2026, Shift 1·Q7·MCQ·Moderate
Open
Two electrons are moving in orbits of two hydrogen like atoms with speeds $3\times10^{5}$ m/s and $2.5\times10^{5}$ m/s respectively. If the radii of these orbits are nearly same then the possible orders of energy states are respectively.
1. (1)6 and 5
2. (2)9 and 8
3. (3)8 and 10
4. (4)10 and 12
We corrected a printing error in the original paper
Source printed “the possible order of energy states are”.
PhysicsJEE Main 2 Apr 2026, Shift 1·Q19·MCQ·Easy–moderate
Open
Angular momentum of an electron in a hydrogen atom is $\dfrac{3h}{\pi}$ , then the energy of the electron is eV.
1. (1) $-1.51$
2. (2) $-0.85$
3. (3) $-0.38$
4. (4) $-0.28$
PhysicsJEE Main 2 Apr 2026, Shift 2·Q22·Numerical·Moderate
Open
Using Bohr's model, calculate the ratio of the magnetic fields generated due to the motion of the electrons in the $2^{\text{nd}}$ and $4^{\text{th}}$ orbits of hydrogen atom .
We corrected a printing error in the original paper
Answer corrected; the source key is (64) — $B = \mu_0 I/2r$ with $I = ev/2\pi r$ gives $B \propto 1/n^5$ , so $B_2/B_4 = 2^5 = 32$ ; the source solution evaluates $4^5/2^5$ as 64.
PhysicsJEE Main 5 Apr 2026, Shift 1·Q11·MCQ·Easy–moderate
Open
In the hydrogen atom, the electron makes a transition from the higher orbit ( $i$ ) to a lower orbit ( $f$ ). The ratio of the radius of the orbits is given by $r_i : r_f = 16 : 4$ . The wavelength of photon emitted due to this transition is nm. (Given Rydberg constant $= 1.0973\times10^{7}$ /m)
1. (1)121
2. (2)242
3. (3)486
4. (4)974
We corrected a printing error in the original paper
Source printed “in given by”.