JEE Main 2021 · ChemistryNumerical answerNumerical valueEasyCalculation

JEE Main 25 July 2021, Shift 2, Chemistry Q58

Question 58 of 90 in this shift, Chemistry question 28 of 30, Section B.

Number of electrons present in 4f orbital of

\mathrm{Ho^{3+}}

ion is ________. (Given Atomic No. of Ho = 67)

Official answer

NTA final key.

Chapter: The d- and f-Block Elements
Topic: f-Block Elements
Idea tested: Lanthanide Electronic Configuration

Same idea in other shifts

Asked 8× in all

4 Apr 2026, Shift 2 · Q59Pairs of elements with the same number of electrons in their respective 4f orbital are [Atomic number: Eu-63, Gd-64, Dy-66, Ho-67, Tm-69,…MediumOther
6 Apr 2024, Shift 1 · Q69The number of element from the following that do not belong to lanthanoids is Eu, Cm, Er, Tb, Yb and LuEasySingle correct
27 Jan 2024, Shift 1 · Q68The electronic configuration for Neodymium is : [Atomic Number for Neodymium 60]EasySingle correct
27 Jun 2022, Shift 2 · Q69The 'f' orbitals are half and completely filled, respectively in lanthanide ions [Given : Atomic no. Eu, 63; Sm, 62; Tm, 69; Tb, 65; Yb,…MediumSingle correct
4 Aug 2021, Shift 1 · Q40Match List I with List II List I List II A. Gadolinium (At. No. 64) I. $5f^7, 6d^1, 7s^2$ B. Holmium (At. No. 67) II. $5f^4, 6d^1, 7s^2$ …MediumMatch the list
9 Jan 2020, Shift 1 · Q36The electronic configurations of bivalent europium and trivalent cerium are : (atomic number : Xe = 54, Ce = 58, Eu = 63)MediumSingle correct
5 Sep 2020, Shift 1 · Q37The correct electronic configuration and spin-only magnetic moment (BM) of $\mathrm{Gd^{3+}}$ ( $Z = 64$ ), respectively, are :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.