JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyApplication

JEE Main 25 July 2021, Shift 1, Chemistry Q39

Question 39 of 90 in this shift, Chemistry question 9 of 30, Section A.

Which one of the following species responds to an external magnetic field ?

(1) $\mathrm{[Fe(H_2O)_6]^{3+}}$ Official answer
(2) $\mathrm{[Ni(CN)_4]^{2-}}$
(3) $\mathrm{[Co(CN)_6]^{3-}}$
(4) $\mathrm{[Ni(CO)_4]}$

Official answer

Option 1

NTA final key.

Chapter: Coordination Compounds
Topic: Crystal Field Theory
Idea tested: High and Low Spin States

Same idea in other shifts

Asked 19× in all

4 Apr 2026, Shift 2 · Q60Consider the metal complexes $\mathrm{[Ni(en)_3]^{2+}}$ (A), $\mathrm{[NiCl_4]^{2-}}$ (B) and $\mathrm{[Ni(NH_3)_6]^{2+}}$ (C). Choose the…MediumSingle correct
5 Apr 2026, Shift 2 · Q71The total number of unpaired electrons present in the $d^3$ , $d^4$ (low spin) $d^5$ (high spin), $d^6$ (high spin) and $d^7$ (low spin)…EasyNumerical value
6 Apr 2026, Shift 2 · Q61Which of the following sequences of hybridisation, geometry and magnetic nature are correct for the given coordination compounds ? A.…MediumOther
8 Apr 2026, Shift 2 · Q71Number of paramagnetic complexes among the following is ________. $[\mathrm{MnBr_4}]^{2-}$ , $[\mathrm{NiCl_4}]^{2-}$ ,…MediumNumerical value
2 Apr 2025, Shift 1 · Q60Given below are two statements : Statement (I) : In octahedral complexes, when $\Delta_o<$ P high spin complexes are formed. When…EasyTwo statements
2 Apr 2025, Shift 1 · Q74A transition metal (M) among Mn, Cr, Co and Fe has the highest standard electrode potential ( $\mathrm{M^{3+}/M^{2+}}$ ). It forms a metal…MediumNumerical value
2 Apr 2025, Shift 2 · Q61The type of hybridization and the magnetic property of $\mathrm{[MnCl_6]^{3-}}$ are,MediumSingle correct
3 Apr 2025, Shift 2 · Q62Identify the diamagnetic octahedral complex ions from below ; A. $[\mathrm{Mn(CN)_6}]^{3-}$ B. $[\mathrm{Co(NH_3)_6}]^{3+}$ C.…MediumOther

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 42 of the 174 JEE Main shifts held from 2017 to 2026.