JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 31 August 2021, Shift 2, Physics Q2

Question 2 of 90 in this shift, Physics question 2 of 30, Section A.

A free electron of

2.6

eV energy collides with a

\mathrm{H^+}

ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. (

h = 6.6\times10^{-34}

J s)

(1) $0.19\times10^{15}$ MHz
(2) $9.0\times10^{27}$ MHz
(3) $1.45\times10^{9}$ MHzOfficial answer
(4) $1.45\times10^{16}$ MHz

Official answer

Option 3

NTA final key.

Chapter: Atoms
Topic: Bohr's Atomic Model
Idea tested: Energy Level Calculations

Same idea in other shifts

Asked 12× in all

2 Apr 2026, Shift 1 · Q44Angular momentum of an electron in a hydrogen atom is $\frac{3h}{\pi}$ , then the energy of the electron is ______ eV.EasySingle correct
2 Apr 2025, Shift 1 · Q43Considering Bohr's atomic model for hydrogen atom : (A) the energy of H atom in ground state is same as energy of $\mathrm{He^+}$ ion in…EasyOther
6 Apr 2024, Shift 1 · Q60Radius of a certain orbit of hydrogen atom is 8.48 Å. If energy of electron in this orbit is $E/x$ , then $x$ = __________. (Given $a_o$ =…EasyNumerical value
6 Apr 2023, Shift 1 · Q34The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength isEasyDiagram basedHas a figure
11 Apr 2023, Shift 2 · Q44The energy of $\mathrm{He^+}$ ion in its first excited state is, (The ground state energy for the Hydrogen atom is $-13.6\ \mathrm{eV}$ ):EasySingle correct
29 Jul 2022, Shift 1 · Q47Find the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its (i) second permitted energy…EasySingle correct
27 Jun 2022, Shift 1 · Q54A beam of monochromatic light is used to excite the electron in $\mathrm{Li^{++}}$ from the first orbit to the third orbit. The wavelength…MediumNumerical value
27 Jun 2022, Shift 2 · Q48Given below are two statements: Statement I: In hydrogen atom, the frequency of radiation emitted when an electron jumps from lower energy…EasyTwo statements

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.