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Redox Reactions

Previous year questions with solutions · 2000 – 2026

25Questions
19Papers covered
2.22% →0%Weightage in 2026
’00
’02
’03
’04
’08
’09
’12
’14
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’18
’19
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’22
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’26
Year-wise statistics questions · papers · average per paper · weightage
YearQuestionsPapersAvg / paperWeightage
20262212.22% →0%
20251112.22% ↑124.4%
2024120.50.99% ↓49.5%
20231111.96% ↑98%
2022120.50.99% ↓50.5%
20211112.00% ↓10%
20201112.22% →0%
20191112.22% ↓66.7%
20183136.67% ↑200%
20152212.22% ↓50%
20142124.44% ↑18.5%
2012321.53.75% ↑91.3%
20091111.96% →0%
20081111.96% ↓5.9%
20041112.08% ↑2.1%
20031112.04% ↑2%
20021112.00% ↑2%
20001111.96%

25 questions · newest paper first

1

In an acidic medium, 10 mL of 0.25 M oxalic acid is titrated with KMnO4 solution. If the volume of KMnO4 solution required to reach end point is 10 mL, the strength of the KMnO4 solution is

  1. 0.15 M
  2. 0.10 M
  3. 0.20 M
  4. 0.25 M
RE-NEET (UG) 2026
2

The correct decreasing order of oxidation state of the underlined atom in each molecule is

  1. P4O6 > Cl2O7 > AlH3
  2. P4O10 > SO3 > H2 O
  3. N2O5 > Al2O3 > H2 S
  4. PbO2 > N2O3 > SO3
RE-NEET (UG) 2026
3

Consider the following compounds : KO2, H2 O2 and H2 SO4 The oxidation state of the underlined elements in them are, respectively,

  1. +1, -2, and +4
  2. +4, -4, and +6
  3. +1, -1, and +6
  4. +2, -2, and +6
NEET (UG) 2025
4

Which reaction is NOT a redox reaction?

  1. Zn + CuSO4 ZnSO4 + Cu
  2. 2KClO3 + I2 2KIO3 + Cl2
  3. H2 + Cl2 2HCl
  4. BaCl2 + Na2SO4 BaSO4 + 2NaCl
NEET (UG) 2024
5

On balancing the given redox reaction, a Cr2O72-(aq) + b SO32-(aq) + cH+(aq) 2a Cr3+(aq) + b SO42-(aq) + c2H2O( ) the coefficients a, b and c are found to be, respectively -

  1. 3, 8, 1
  2. 1, 8, 3
  3. 8, 1, 3
  4. 1, 3, 8
NEET (UG) 2023
6

Which of the following reactions is a decomposition redox reaction?

  1. P4(s) + 3OH-(aq) + 3H2O(l) PH3(g) + 3H2PO2-(aq)
  2. 2Pb(NO3)2(s) 2PbO(s) + 4NO2(g) + O2(g)
  3. N2(g) + O2(g) 2NO(g)
  4. Cl2(g) + 2OH-(aq) ClO-(aq) + Cl-(aq) + H2O(l)
NEET (UG) 2022 (Phase 2)
7

Which of the following reactions is the metal displacement reaction? Choose the right option.

  1. 2Pb(NO3)2 2PbO + 4NO2 + O2
  2. 2KClO3 2KCl + 3O2
  3. Cr2O3 + 2Al Al2O3 + 2Cr
  4. Fe + 2HCl FeCl2 + H2
NEET (UG) 2021
8

What is the change in oxidation number of carbon in the following reaction? CH4(g) + 4Cl2(g) CCl4(l) + 4HCl(g)

  1. 0 to +4
  2. -4 to +4
  3. 0 to -4
  4. +4 to +4
NEET (UG) 2020
9

Which of the following reactions are disproportionation reaction? Select the correct option from the following :

  1. A, C and D
  2. A and B only
  3. A and D only
  4. A, B and C
NEET (UG) 2019
10

Consider the change in oxidation state of bromine corresponding to different emf values as shown in the given diagram : BrO4- 1.82 V BrO3- 1.5 V HBrO 1.595 V Br2 1.0652 V Br- Then the species undergoing disproportionation is :

  1. BrO4-
  2. BrO3-
  3. Br2
  4. HBrO
NEET 2018
11

The correct order of N-compounds in its decreasing order of oxidation states is

  1. HNO3, NO, N2, NH4Cl
  2. HNO3, NO, NH4Cl, N2
  3. HNO3, NH4Cl, NO, N2
  4. NH4Cl, N2, NO, HNO3
NEET 2018
12

For the redox reaction, MnO4- + C2O42- + H+ Mn2+ + CO2 + H2O The correct coefficients of the reactants for the balanced equation are

  1. array|c|c|c| MnO4- & C2O42- & H+ \ 16 & 5 & 2 \ array
  2. array|c|c|c| MnO4- & C2O42- & H+ \ 2 & 5 & 16 \ array
  3. array|c|c|c| MnO4- & C2O42- & H+ \ 2 & 16 & 5 \ array
  4. array|c|c|c| MnO4- & C2O42- & H+ \ 5 & 16 & 2 \ array
NEET 2018
13

Assuming complete ionisation, same moles of which of the following compounds will require the least amount of acidified KMnO4 for complete oxidation?

  1. FeSO3
  2. FeC2O4
  3. Fe(NO2)2
  4. FeSO4
AIPMT 2015
14

Which of the following processes does not involve oxidation of iron?

  1. Formation of Fe(CO)5 from Fe.
  2. Liberation of H2 from steam by iron at high temperature.
  3. Rusting of iron sheets.
  4. Decolourisation of blue CuSO4 solution by iron.
AIPMT 2015 (Cancelled)
15

The pair of compounds that can exist together is

  1. FeCl3, SnCl2
  2. HgCl2, SnCl2
  3. FeCl2, SnCl2
  4. FeCl3, KI
AIPMT 2014
16

In acidic medium, H2O2 changes Cr2O72- to CrO5 which has two (-O-O-) bonds. Oxidation state of Cr in CrO5 is

  1. +5
  2. +3
  3. +6
  4. -10
AIPMT 2014
17

When Cl2 gas reacts with hot and concentrated sodium hydroxide solution, the oxidation number of chlorine changes from

  1. zero to +1 and zero to −5
  2. zero to −1 and zero to +5
  3. zero to −1 and zero to +3
  4. zero to +1 and zero to −3
AIPMT 2012 (Prelims)
18

A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?

  1. S
  2. H
  3. Cl
  4. C
AIPMT 2012 (Prelims)
19

In which of the following compounds, nitrogen exhibits highest oxidation state?

  1. N2H4
  2. NH3
  3. N3H
  4. NH2OH
AIPMT 2012 (Prelims)
20

Oxidation numbers of P in PO43-, of S in SO42- and that of Cr in Cr2O72- are respectively

  1. +3, +6 and +5
  2. +5, +3 and +6
  3. –3, +6 and +6
  4. +5, +6 and +6
AIPMT 2009
21

Number of moles of MnO4- required to oxidize one mole of ferrous oxalate completely in acidic medium will be

  1. 7.5 moles
  2. 0.2 moles
  3. 0.6 moles
  4. 0.4 moles
AIPMT 2008
22

Which is the best description of the behaviour of bromine in the reaction given below? H2O + Br2 HOBr + HBr

  1. Proton acceptor only
  2. Both oxidised and reduced
  3. Oxidised only
  4. Reduced only
AIPMT 2004
23

The oxidation states of sulphur in the anions SO32-, S2O42- and S2O62- follow the order

  1. S2O42- < SO32- < S2O62-
  2. SO32- < S2O42- < S2O62-
  3. S2O42- < S2O62- < SO32-
  4. S2O62- < S2O42- < SO32-
AIPMT 2003
24

Which reaction is not feasible?

  1. 2KI + Br2 2KBr + I2
  2. 2KBr + I2 2KI + Br2
  3. 2KBr + Cl2 2KCl + Br2
  4. 2H2O + 2F2 4HF + O2
AIPMT 2002
25

Oxidation numbers of A, B, C are +2, +5 and -2 respectively. Possible formula of compound is

  1. A2(BC2)2
  2. A3(BC4)2
  3. A2(BC3)2
  4. A3(B2C)2
AIPMT 2000