Quantrex Academy Quantrex AcademyPYQs with solutions · JEE · NEET · NDA

Home · JEE Main & Advanced · Chemistry · Redox Reactions

Redox Reactions — JEE Main & Advanced Chemistry PYQs

295 previous year questions from Redox Reactions with answers and solutions. Numbered list, year tags, and one-tap solutions — built for serious JEE / NEET practice.

295 questionsChemistrySolutions on every page
1

500 mL of 0.2 M MnO₄^- solution in basic medium when mixed with 500 mL of 1.5 M KI solution, oxidises iodide ions to liberate molecular iodine. This liberated iodine is then titrat

JEE Main 2026 Solution View → 2

Given below are two statements: Statement I: Sodium dichromate and potassium dichromate are classified as primary standards in titrimetric analysis. Statement II: Phenolphthalein i

JEE Main 2026 Solution View → 3

In order to oxidise a mixture of 1 mole each of FeC₂O₄ , Fe₂(C₂O₄)₃ , FeSO₄ and Fe₂(SO₄)₃ in acidic medium, the number of moles of KMnO₄ required is

JEE Main 2026 Solution View → 4

500 mL of 1.2 M KI solution is mixed with 500 mL of 0.2 M KMnO ₄ solution in basic medium. The liberated iodine was titrated with standard 0.1 M Na ₂ ~S ₂ O ₃ solution in the prese

JEE Main 2026 Solution View → 5

One mole of Cl ₂( ~g ) was passed into 2 L of cold 2 M KOH solution. After the reaction, the concentrations of Cl ⁻, ClO ⁻ and OH ⁻ are respectively (assume volume remains constant

JEE Main 2026 Solution View → 6

X and Y are the number of electrons involved, respectively during the oxidation of I ⁻ to I ₂ and S ²⁻ to S by acidified K ₂ Cr ₂ O ₇ . The value of X + Y is _ _ _ _ .

JEE Main 2026 Solution View → 7

200 cc of x 10⁻³ M potassium dichromate is required to oxidise 750 cc of 0.6 M Mohr's salt solution in acidic medium. Here x= _ _ _ _ .

JEE Main 2026 Solution View → 8

Identify the correct statements : A. Hydrated salts can be used as primary standard. B. Primary standard should not undergo any reaction with air. C. Reactions of primary standard

JEE Main 2026 Solution View → 9

One of the products formed from the reaction of permanganate ion with iodide ion in neutral aqueous medium is

JEE Advanced 2025 Solution View → 10

Compounds that should not be used as primary standards in titrimetric analysis are : A. Na ₂ Cr ₂ O ₇ B. Oxalic acid C. NaOH D. FeSO ₄ 6 H ₂ O E. Sodium tetraborate Choose the most

JEE Main 2025 Solution View → 11

0.1 M solution of KI reacts with excess of H ₂ SO ₄ and KIO ₃ solutions. According to equation 5 I ⁻+ IO ₃⁻+6 H ⁺ 3 I ₂+3 H ₂ O Identify the correct statements : (A) 200 mL of KI s

JEE Main 2025 Solution View → 12

Match the List-I with List-II Choose the correct answer from the options given below:

JEE Main 2025 Solution View → 13

Given below are two statements: Statement I: In the oxalic acid vs KMnO ₄ (in the presence of dil H ₂ SO ₄ ) titration the solution needs to be heated initially to 60^ C , but no h

JEE Main 2025 Solution View → 14

The species which does not undergo disproportionation reaction is :

JEE Main 2025 Solution View → 15

Some CO ₂ gas was kept in a sealed container at a pressure of 1 atm and at 273 K . This entire amount of CO ₂ gas was later passed through an aqueous solution of Ca ( OH )₂ . The e

JEE Main 2025 Solution View → 16

In a metal deficient oxide sample, M _ x Y ₂ O ₄ ( M and Y are metals), M is present in both +2 and +3 oxidation states and Y is in +3 oxidation state. If the fraction of M ²⁺ ions

JEE Advanced 2024 Solution View → 17

At room temperature, disproportionation of an aqueous solution of in situ generated nitrous acid ( HNO ₂ ) gives the species

JEE Advanced 2024 Solution View → 18

Identify the incorrect statements regarding primary standard of titrimetric analysis. (A) It should be purely available in dry form. (B) It should not undergo chemical change in ai

JEE Main 2024 Solution View → 19

Among the following halogens ( F ₂, Cl ₂, Br ₂ ) and ( I ₂ ) Which can undergo disproportionation reactions?

JEE Main 2024 Solution View → 20

Thiosulphate reacts differently with iodine and bromine in the reactions given below: ( aligned & 2 ~S ₂ O ₃²⁻+ I ₂ S ₄ O ₆²⁻+2 I ⁻ & S ₂ O ₃²⁻+5 Br ₂+5 H ₂ O 2 SO ₄²⁻+4 Br ⁻+10 H

JEE Main 2024 Solution View → 21

Match List - I with List - II. ( array ll List - I & List - II Reaction & Type of redox reaction (A) N _ 2( ~g ) + O _ 2( ~g ) 2 NO _ ( g ) & (I) Decomposition (B) 2 ~Pb ( NO ₃ )_

JEE Main 2024 Solution View → 22

Only (2 ~mL ) of ( KMnO ₄ ) solution of unknown molarity is required to reach the end point of a titration of (20 ~mL ) of oxalic acid ((2 M ) ) in acidic medium. The molarity of (

JEE Main 2024 Solution View → 23

Which of the following reactions are disproportionation reactions? 1 Cu + → Cu 2 + + Cu 2 3 MnO 4 2 - + 4 H + → 2 MnO 4 - + MnO 2 + 2 H 2 O 3 2 KMnO 4 → K 2 MnO 4 + MnO 2 + O 2 4 2

JEE Main 2024 Solution View → 24

In acidic medium, K 2 Cr 2 O 7 shows oxidising action as represented in the half reaction Cr 2 O 7 2 - + XH + + Ye - → 2 A + ZH 2 O X , Y , Z and A are respectively are:

JEE Main 2024 Solution View → 25

Given below are two statements : Statement (I) : Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution. Statement (II) : In this titra

JEE Main 2024 Solution View → 26

Given below are two statements : Statement I: S 8 solid undergoes disproportionation reaction under alkaline conditions to form S 2 − and S 2 O 3 2 − Statement II: ClO 4 − can unde

JEE Main 2024 Solution View → 27

Total number of species from the following which can undergo disproportionation reaction ___________. H 2 O 2 , ClO 3 - , P 4 , Cl 2 , Ag , Cu + 1 , F 2 , NO 2 , K +

JEE Main 2024 Solution View → 28

2 MnO 4 - + bI - + cH 2 O → xI 2 + yMnO 2 + zOH - If the above equation is balanced with integer coefficients, the value of z is ________.

JEE Main 2024 Solution View → 29

If 50 mL of 0 . 5 M oxalic acid is required to neutralise 25 mL of NaOH solution, the amount of NaOH in 50 mL of given NaOH solution is_______g.

JEE Main 2024 Solution View → 30

Chlorine undergoes disproportionation in alkaline medium as shown below : aCl 2 ( g ) + bOH - ( aq ) → cClO - ( aq ) + dCl - ( aq ) + eH 2 O ( l ) The values of a , b , c and d in

JEE Main 2024 Solution View → 31

KMnO 4 decomposes on heating at 513 K to form O 2 along with

JEE Main 2024 Solution View → 32

Which of the following cannot function as an oxidising agent?

JEE Main 2024 Solution View → 33

H 2 S ( 5 moles) reacts completely with acidified aqueous potassium permanganate solution. In this reaction, the number of moles of water produced is x , and the number of moles of

JEE Advanced 2023 Solution View → 34

Consider the following molecules : Br 3 O 8 ,   F 2 O , H 2   S 4 O 6 , H 2   S 5 O 6 , and C 3 O 2 . Count the number of atoms existing in their zero oxidation stat

JEE Advanced 2023 Solution View → 35

The total change in the oxidation state of manganese involved in the reaction of KMnO 4 and potassium iodide in the acidic medium is ________.

JEE Main 2023 Solution View → 36

See the following chemical reaction: Cr 2 O 7 2 - + XH + + 6 Fe 2 + → YCr 3 + + 6 Fe 3 + + ZH 2 O The sum of X, Y and Z is

JEE Main 2023 Solution View → 37

KMnO 4 is titrated with ferrous ammonium sulphate hexahydrate in presence of dilute H 2 SO 4 . Number of water molecules produced for 2 molecules of KMnO 4 is _ _ _ _ _ _ _

JEE Main 2023 Solution View → 38

20 mL of calcium hydroxide was consumed when it was reacted with 10 mL of unknown solution of H 2 SO 4 . Also 20 mL standard solution of 0 . 5 M HCl containing 2 drops of phenolpht

JEE Main 2023 Solution View → 39

In alkaline medium, the reduction of permanganate anion involves a gain of ____________ electrons.

JEE Main 2023 Solution View → 40

Given below are two statements: Statement I: In redox titration, the indicators used are sensitive to change in pH of the solution. Statement II: In acid-base titration, the indica

JEE Main 2023 Solution View → 41

2 IO 3 - + xI - + 12 H + → 6 I 2 + 6 H 2 What is the value of x ?

JEE Main 2023 Solution View → 42

During the reaction of permanganate with thiosulphate, the change in oxidation of manganese occurs by value of 3 . Identify which of the below medium will favour the reaction.

JEE Main 2023 Solution View → 43

The volume of 0 . 02 M aqueous HBr required to neutralize 10 . 0 mL of 0 . 01 M aqueous Ba ( OH ) 2 is (Assume complete neutralization)

JEE Main 2023 Solution View → 44

Which of the following options are correct for the reaction? 2 Au ( CN ) 2 - ( aq ) + Zn ( s ) → 2 Au ( s ) + Zn ( CN ) 4 2 - ( aq ) A. Redox reaction B. Displacement reactio

JEE Main 2023 Solution View → 45

Strong reducing and oxidizing agents among the following , respectively, are

JEE Main 2023 Solution View → 46

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : An aqueous solution of KOH when for volumetric analysis, i

JEE Main 2023 Solution View → 47

The density of a monobasic strong acid (Molar mass 24 . 2 g mol ) is 1 . 21 kg L . The volume of its solution required for the complete neutralization of 25 mL of 0 . 24 M NaOH is

JEE Main 2023 Solution View → 48

Choose the correct representation of conductometric titration of benzoic acid vs sodium hydroxide.

JEE Main 2023 Solution View → 49

A compound ' X ' is a weak acid and it exhibits colour change at pH close to the equivalence point during neutralization of NaOH with CH 3 COOH . Compound ' X ' exi

JEE Main 2022 Solution View → 50

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R Assertion A : Permanganate titration are not performed in presence of hydrochlo

JEE Main 2022 Solution View → 51

The normality of H 2 SO 4 in the solution obtained on mixing 100   mL of 0 . 1 M   H 2 SO 4 with 50   mL of 0 . 1 M   NaOH is____ × 10 - 1   N .

JEE Main 2022 Solution View → 52

20 mL of 0 . 02 MK 2 Cr 2 O 7 solution is used for the titration of 10 mL of Fe 2 + solution in the acidic medium. The molarity of Fe 2 + solution is____ × 10 - 2 M

JEE Main 2022 Solution View → 53

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R . Assertion A :Phenolphthalein is a pH dependent indicator, remains colourless

JEE Main 2022 Solution View → 54

20   mL of 0 . 02   M hypo solution is used for the titration of 10   mL of copper sulphate solution, in the presence of excess of KI using starch as an indicator. T

JEE Main 2022 Solution View → 55

Which of the given reactions is not an example of disproportionation reaction?

JEE Main 2022 Solution View → 56

For the reaction given below: CoCl 3 . xNH 3 + AgNO 3 aq → If two equivalents of AgCl precipitate out, then the value of x will be _______

JEE Main 2022 Solution View → 57

0 . 01 MKMnO 4 solution was added to 20 . 0 mL of 0 . 05 M Mohr 's salt solution through a burette. The initial reading of 50 mL burette is zero. The volume of KMnO 4 solution

JEE Main 2022 Solution View → 58

A 2 . 0 g sample containing MnO 2 is treated with HCl liberating Cl 2 . The Cl 2 gas is passed into a solution of KI and 60 . 0 mL of 0 . 1 MNaS 2 O 3 is required to titrate the li

JEE Main 2022 Solution View → 59

Which one of the following is an example of disproportionation reaction?

JEE Main 2022 Solution View → 60

The neutralization occurs when 10   mL of 0 . 1   M acid ' A ' is allowed to react with 30   mL of 0 . 05   M base M OH 2 . The basicity of the acid &#3

JEE Main 2022 Solution View → 61

Manganese VI has ability to disproportionate in acidic solution. The difference in oxidation states of two ions it forms in acidic solution is

JEE Main 2022 Solution View → 62

A 0 . 166   g sample of an organic compound was digested with conc. H 2 SO 4 and then distilled with NaOH . The ammonia gas evolved was passed through 50 . 0   mL of 0 .

JEE Main 2022 Solution View → 63

A sample (5.6 ~g ) containing iron is completely dissolved in cold dilute HCl to prepare a 250 ~mL of solution. Titration of 25.0 ~mL of this solution requires 12.5 ~mL of 0.03 M K

JEE Advanced 2021 Solution View → 64

A sample (5.6 ~g ) containing iron is completely dissolved in cold dilute HCl to prepare a 250 ~mL of solution. Titration of 25.0 ~mL of this solution requires 12.5 ~mL of 0.03 M K

JEE Advanced 2021 Solution View → 65

In which one of the following sets all species show disproportionation reaction?

JEE Main 2021 Solution View → 66

In polythionic acid, H 2 S x O 6 ( x = 3 to 5 ) the oxidation state(s) of sulphur is/are:

JEE Main 2021 Solution View → 67

10 . 0 mL of 0 . 05 M KMnO 4 solution was consumed in a titration with 10 . 0 mL of given oxalic acid dihydrate solution. The strength of given oxalic acid solution is ........ &#2

JEE Main 2021 Solution View → 68

The oxidation states of ' P ' in H 4 P 2 O 7 , H 4 P 2 O 5 and H 4 P 2 O 6 , respectively, are :

JEE Main 2021 Solution View → 69

Identify the process in which change in the oxidation state is five :

JEE Main 2021 Solution View → 70

When 10   mL of an aqueous solution of Fe 2 + ions was titrated in the presence of dil H 2 SO 4 using diphenylamine indicator, 15   mL of 0 . 02   M solution of K 2

JEE Main 2021 Solution View → 71

Cu 2 + salt reacts with potassium iodide to give

JEE Main 2021 Solution View → 72

4 g equimolar mixture of NaOH and Na 2 CO 3 contains xg of NaOH and yg of Na 2 CO 3 . The value of x is g . (Nearest integer)

JEE Main 2021 Solution View → 73

The species given below that does NOT show disproportionation reaction is:

JEE Main 2021 Solution View → 74

250 mL of 0 . 5 M NaOH was added to 500 mL of 1 M HCl . The number of unreacted HCl molecules in the solution after the complete reaction is p × 10 21 . Find out p (Nearest in

JEE Main 2021 Solution View → 75

The oxidation states of nitrogen in NO , NO 2 , N 2 O and NO 3 - are in the order of :

JEE Main 2021 Solution View → 76

15   mL of aqueous solution of Fe 2 + in acidic medium completely reacted with 20   mL of 0 . 03   M aqueous Cr 2 O 7 2 - . The molarity of the Fe 2 + solution is __

JEE Main 2021 Solution View → 77

The exact volumes of 1 M NaOH solution required to neutralise 50 mL of 1 M H 3 PO 3 solution and 100 mL of 2 M H 3 PO 2 solution, respectively, are :

JEE Main 2021 Solution View → 78

2 MnO 4 - + bC 2 O 4 2 - + cH + → xMn 2 + + yCO 2 + zH 2 O If the above equation is balanced with integer coefficients, the value of c is _______ . (Round off to the Nearest

JEE Main 2021 Solution View → 79

In mildly alkaline medium, thiosulphate ion is oxidized by MnO 4 - to " A " . The oxidation state of sulphur in " A " is_

JEE Main 2021 Solution View → 80

Dichromate ion is treated with base, the oxidation number of Cr in the product formed is

JEE Main 2021 Solution View → 81

Consider titration of NaOH solution versus 1 . 25 M oxalic acid solution. At the end point following burette readings were obtained. (i) 4 . 5 mL (ii) 4 . 5 mL (iii) 4 . 4 mL (iv)

JEE Main 2021 Solution View → 82

0 . 4 g mixture of NaOH , Na 2 CO 3 and some inert impurities was first titrated with N 10 HCl using phenolphthalein as an indicator, 17 . 5 mL of HCl was required at the end point

JEE Main 2021 Solution View → 83

In basic medium CrO 4 2 - oxidises S 2 O 3 2 - to form SO 4 2 - and itself changes into Cr OH 4 - .The volume of 0 . 154 MCrO 4 2 - required to react with 40 mL of 0 . 25 MS 2 O 3

JEE Main 2021 Solution View → 84

(A) HOCl + H 2 O 2 → H 3 O + + Cl - + O 2 (B) I 2 + H 2 O 2 + 2 OH - → 2 I - + 2 H 2 O + O 2 Choose the correct option.

JEE Main 2021 Solution View → 85

The reaction of sulphur in alkaline medium is given below: S 8 s + a OH aq − → b S aq 2 − + c S 2 O 3 aq 2 − + d H 2 O l The values of ' a ' is_____

JEE Main 2021 Solution View → 86

In the chemical reaction between stoichiometric quantities of KMnO 4 KI in weakly basic solution, what is the number of moles of I 2 released for 4 KMnO 4 consumed?

JEE Advanced 2020 Solution View → 87

An acidified solution of potassium chromate was layered with an equal volume of amyl alcohol. When it was shaken after the addition of 1   mL of 3 %   H 2 O 2 , a blue al

JEE Advanced 2020 Solution View → 88

Choose the correct statement(s) among the following.

JEE Advanced 2020 Solution View → 89

5 . 00   mL of 0 . 10   M oxalic acid solution taken in a conical flask is titrated against NaOH from a burette using phenolphthalein indicator. The volume of NaOH requir

JEE Advanced 2020 Solution View → 90

The volume, in mL , of 0 . 02 MK 2 Cr 2 O 7 , solution required to react with 0 . 288 g of ferrous oxalate in acidic medium is … … … … (Molar mass of Fe = 5

JEE Main 2020 Solution View → 91

A 20 . 0   mL solution containing 0 . 2   g impure H 2 O 2 reacts completely with 0 . 316   g of KMnO 4 in acid solution. The purity of H 2 O 2 (in % ) is______ (mol

JEE Main 2020 Solution View → 92

100 mL of 0 . 1 M HCl is taken in a beaker and to it 100 mL 0 . 1 M NaOH of is added in steps of 2 mL and the pH is continuously measured. Which of the following graphs correctly d

JEE Main 2020 Solution View → 93

The oxidation states of transition metal atoms in K 2 Cr 2 O 7 , KMnO 4 and K 2 FeO 4 , respectively, are x , y and z . The sum of x , y and z is______

JEE Main 2020 Solution View → 94

While titration dilute HCI solution with aqueous NaOH , which of the following will not be required ?

JEE Main 2020 Solution View → 95

The compound that cannot act both as oxidizing and reducing agent is

JEE Main 2020 Solution View → 96

The strength of an aqueous N a O H solution is most accurately determined by titrating: (Note: consider that an appropriate indicator is used)

JEE Main 2020 Solution View → 97

The redox reaction among the following is

JEE Main 2020 Solution View → 98

Consider the following reactions: NaCl + K 2 Cr 2 O 7 + H 2 SO 4 Conc. → A + side products A + N a O H → B + side products B + H 2 S O 4 dilute + H 2 O 2 → C + si

JEE Main 2020 Solution View → 99

Oxidation number of potassium in K 2 O , K 2 O 2 and K O 2 , respectively, is:

JEE Main 2020 Solution View → 100

2.68 × 10 − 3 moles of a solution containing an ion A n+ require 1 .61 × 10 − 1 moles of MnO 4 - ion for the oxidation of A n+ to AO 3 - in acidic medium. What is the value of n?

NTA Abhyas JEE Main 2020 Solution View → 101

Select the nature or type of redox change in the following reaction:- C l 2 → C l O - + C l -

NTA Abhyas JEE Main 2020 Solution View → 102

A 2.0 g sample of a mixture containing sodium carbonate, sodium bicarbonate and sodium sulphate is gently heated till the evolution of CO 2 ceases. The volume of CO 2 at 750 mm Hg

NTA Abhyas JEE Main 2020 Solution View → 103

2.56 × 10 - 3 equivalent of KOH is required to neutralise 0 .12544 g H 2 XO 4 . The atomic mass of X (in g/mol ) is: [Given: H 2 XO 4 is a dibasic acid]

NTA Abhyas JEE Main 2020 Solution View → 104

1 mole of equimolar mixture of Fe 2 (C 2 O 4 ) 3 and FeC 2 O 4 requires X moles of KMnO 4 in acid medium for complete reaciton. The value of X is:

NTA Abhyas JEE Main 2020 Solution View → 105

5 mol of F e 2 ( C 2 O 4 ) 3 is oxidised by x mol of K 2 C r 2 O 7 in acidic medium, calculate the value of X ?

NTA Abhyas JEE Main 2020 Solution View → 106

Which of the following acts as an oxidising as well as reducing agent?

NTA Abhyas JEE Main 2020 Solution View → 107

The colour change of an indicator HIn in acid base titrations is given below Which of the following statement is correct?

NTA Abhyas JEE Main 2020 Solution View → 108

The unbalanced equation for the reaction of P 4 S 3 with nitrate in aqueous acidic medium is given below. P 4 S 3 + N O 3 - → H 3 P O 4 + S O 4 2 - + N O The number of moles of wat

NTA Abhyas JEE Main 2020 Solution View → 109

The redox reaction among the following is

NTA Abhyas JEE Main 2020 Solution View → 110

A redox reaction always involves

NTA Abhyas JEE Main 2020 Solution View → 111

Aqueous solution of orthoboric acid can be titrated against sodium hydroxide using phenolphthalein indicator only in presence of:

NTA Abhyas JEE Main 2020 Solution View → 112

How many millilitres of 0 .5 M H 2 SO 4 are needed to dissolve 0 .5 g of copper(II)carbonate? Report your answer by rounding it up to nearest integer.

NTA Abhyas JEE Main 2020 Solution View → 113

The table below gives the results of three titrations carried out with 0.200 M HCl to determine the molarity of a given NaOH solution using phenolphthalein as indicator. NaOH was t

NTA Abhyas JEE Main 2020 Solution View → 114

0 .1 M K M n O 4 is used for following titration. What volume of the solution in mL will be required to react with 0 .158 g of N a 2 S 2 O 3 ? Not balanced: S 2 O 3 2 - + M n O 4 -

NTA Abhyas JEE Main 2020 Solution View → 115

Equal masses of methane and ethane have their total translational kinetic energy in the ratio 3 : 1, then their temperatures are in the ratio is

NTA Abhyas JEE Main 2020 Solution View → 116

In the mixture of N a 2 C O 3 + N a H C O 3 volume of H C l required is x m L with phenolphthalein indicator and y m L with methyl orange indicator in the same titration. Hence vol

NTA Abhyas JEE Main 2020 Solution View → 117

What will be the value of x, y and z in the following equation? H 2 C 2 O 4 + x H 2 O 2 → y C O 2 + z H 2 O

NTA Abhyas JEE Main 2020 Solution View → 118

Find out the compounds that will disproportionate in their aqueous solution. I ClO 4 - ⁡ → + 0.36 V ClO 3 - ⁡ → + 0.33 V C l O 2 → + 0.66 V O C l - → + 0.40 V 1 2 C l 2 → + 1.36 V

NTA Abhyas JEE Main 2020 Solution View → 119

25 m L of household bleach solution was mixed with 30 m L of 0.50 M K I and 10 m L of 4 N acetic acid. In the titration of the liberated iodine, 48 m L of 0.25 N N a 2 S 2 O 3 was

NTA Abhyas JEE Main 2020 Solution View → 120

One mole of N 2 H 4 looses ten moles of electrons to form a new compound Y. Assuming that all the nitrogen appears in the new compound, what is the oxidation state of nitrogen in Y

NTA Abhyas JEE Main 2020 Solution View →
Practice all Redox Reactions questions in the app →