JEE Main 2021 · ChemistryMultiple choiceSingle correctMediumRecall

JEE Main 26 August 2021, Shift 1, Chemistry Q41

Question 41 of 90 in this shift, Chemistry question 11 of 30, Section A.

Which one of the following complexes is violet in colour ?

(1) $[\mathrm{Fe(SCN)_6}]^{4-}$
(2) $[\mathrm{Fe(CN)_5\,NOS}]^{4-}$ Official answer
(3) $\mathrm{Fe_4[Fe(CN)_6]_3 \cdot H_2O}$
(4) $[\mathrm{Fe(CN)_6}]^{4-}$

Official answer

Option 2

NTA final key.

Chapter: Coordination Compounds
Topic: Anion Analysis
Idea tested: Sulfide Sodium Nitroprusside Test

Same idea in other shifts

Asked 4× in all

2 Apr 2025, Shift 2 · Q62Formation of $\mathrm{Na_4[Fe(CN)_5NOS]}$ , a purple coloured complex formed by addition of sodium nitroprusside in sodium carbonate…EasySingle correct
28 Jun 2022, Shift 1 · Q80The formula of the purple colour formed in Laissaigne’s test for sulphur using sodium nitroprusside isEasySingle correct
4 Aug 2021, Shift 2 · Q50The reagent that gives purple coloured complex with $\mathrm{S^{2-}}$ ion isEasySingle 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.