Learn

Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 24 February 2021, Shift 2, Chemistry Q31

Question 31 of 90 in this shift, Chemistry question 1 of 30, Section A.

According to Bohr's atomic theory : (A) Kinetic energy of electron is ∝Z2n2\propto \frac{Z^2}{n^2}. (B) The product of velocity (v) of electron and principal quantum number (n), 'vn' ∝Z2\propto Z^2. (C) Frequency of revolution of electron in an orbit is ∝Z3n3\propto \frac{Z^3}{n^3}. (D) Coulombic force of attraction on the electron is ∝Z3n4\propto \frac{Z^3}{n^4}. Choose the most appropriate\textbf{most appropriate} answer from the options given below :
  1. (1)(A), (C) and (D) only
  2. (2)(A) and (D) onlyOfficial answer
  3. (3)(C) only
  4. (4)(A) only

Official answer

Option 2

NTA final key.

Chapter
Structure of Atom
Topic
Bohr's Atomic Theory
Idea tested
Total, Kinetic, and Potential Energy

Same idea in other shifts

Asked 4× in all
  1. 8 Apr 2025, Shift 2 · Q72The 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…EasyNumerical value
  2. 6 Apr 2024, Shift 2 · Q81For hydrogen atom, energy of an electron in first excited state is −3.4-3.4 eV, K.E. of the same electron of hydrogen atom is xx eV. Value…EasyNumerical value
  3. 13 Apr 2023, Shift 1 · Q61The energy of an electron in the first Bohr orbit of hydrogen atom is −2.18×10−18-2.18\times10^{-18} J. Its energy in the third Bohr orbit…EasySingle correct

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.