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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyCalculation

JEE Main 25 July 2021, Shift 2, Chemistry Q32

Question 32 of 90 in this shift, Chemistry question 2 of 30, Section A.

Identify the process in which change in the oxidation state is five :
  1. (1)Cr2O72−→2Cr3+\mathrm{Cr_2O_7^{2-} \rightarrow 2Cr^{3+}}
  2. (2)MnO4−→Mn2+\mathrm{MnO_4^{-} \rightarrow Mn^{2+}}Official answer
  3. (3)CrO42−→Cr3+\mathrm{CrO_4^{2-} \rightarrow Cr^{3+}}
  4. (4)C2O42−→2CO2\mathrm{C_2O_4^{2-} \rightarrow 2CO_2}

Official answer

Option 2

NTA final key.

Chapter
Redox Reactions
Topic
Redox Reactions
Idea tested
Oxidation Number Assignment

Same idea in other shifts

Asked 9× in all
  1. 9 Apr 2024, Shift 1 · Q65Given below are two statements : Statement (I) : The oxidation state of an element in a particular compound is the charge acquired by its…MediumTwo statements
  2. 27 Jan 2024, Shift 1 · Q85From the given list, the number of compounds with +4 oxidation state of Sulphur is __________.…EasyNumerical value
  3. 6 Apr 2023, Shift 1 · Q90In ammonium – phosphomolybdate, the oxidation state of Mo is + ________MediumNumerical value
  4. 15 Apr 2023, Shift 1 · Q90In Chromyl chloride, the oxidation state of chromium is (+) __________.EasyNumerical value
  5. 27 Jul 2022, Shift 1 · Q88In the titration of KMnO4\mathrm{KMnO_4} and oxalic acid in acidic medium, the change in oxidation number of carbon at the end point is _____EasyNumerical value
  6. 24 Jun 2022, Shift 1 · Q86The difference in oxidation state of chromium in chromate and dichromate salts is ______.EasyNumerical value
  7. 27 Aug 2021, Shift 1 · Q39In polythionic acid, H2SxO6\mathrm{H_2S_xO_6} (xx = 3 to 5) the oxidation state(s) of sulphur is/are :MediumSingle correct
  8. 18 Mar 2021, Shift 2 · Q38The oxidation states of nitrogen in NO, NO2\mathrm{NO_2}, N2O\mathrm{N_2O} and NO3−\mathrm{NO_3^-} are in the order of :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.