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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceMatch the listMediumRecall

JEE Main 4 August 2021, Shift 1, Chemistry Q40

Question 40 of 90 in this shift, Chemistry question 10 of 30, Section A.

Match List I with List II List I List II A. Gadolinium (At. No. 64) I. 5f7,6d1,7s25f^7, 6d^1, 7s^2 B. Holmium (At. No. 67) II. 5f4,6d1,7s25f^4, 6d^1, 7s^2 C. Neptunium (At. No. 93) III. 4f11,6s24f^{11}, 6s^2 D. Curium (At. No. 96) IV. 4f7,5d1,6s24f^7, 5d^1, 6s^2 Choose the correct answer from the options given below :
  1. (1)A–I, B–II, C–III, D–IV
  2. (2)A–IV, B–III, C–II, D–IOfficial answer
  3. (3)A–III, B–IV, C–I, D–II
  4. (4)A–II, B–I, C–IV, D–III

Official answer

Option 2

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
  1. 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
  2. 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
  3. 27 Jan 2024, Shift 1 · Q68The electronic configuration for Neodymium is : [Atomic Number for Neodymium 60]EasySingle correct
  4. 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
  5. 25 Jul 2021, Shift 2 · Q58Number of electrons present in 4f orbital of Ho3+\mathrm{Ho^{3+}} ion is ________. (Given Atomic No. of Ho = 67)EasyNumerical value
  6. 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
  7. 5 Sep 2020, Shift 1 · Q37The correct electronic configuration and spin-only magnetic moment (BM) of Gd3+\mathrm{Gd^{3+}} (Z=64Z = 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.