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Redox Reactions — NEET UG Chemistry PYQs

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

421 questionsChemistrySolutions on every page
1

Calculate the oxidation number of sulfur in H ₂ SO ₄ .

MHT CET Medical 2026 Solution View → 2

Consider the following compounds : K O ₂, H ₂ O ₂ and H ₂ S O ₄ The oxidation state of the underlined elements in them are respectively,

MHT CET Medical 2026 Solution View → 3

What is the oxidation number of phosphorus in Mg ₂ P ₂ O ₇ ?

MHT CET Medical 2026 Solution View → 4

Identify oxidant and reductant, respectively, in the following reaction: Zn (s) + Cu ²⁺(aq) Zn ²⁺(aq) + Cu (s)

MHT CET Medical 2026 Solution View → 5

Which of the following is true regarding oxidation?

MHT CET Medical 2026 Solution View → 6

In a reaction, 2 H ₂ S + SO ₂ 2 H ₂ O + 3 S Identify the substance oxidized.

MHT CET Medical 2026 Solution View → 7

Predict the oxidation number of of 'C' in K ₂ C ₂ O ₄ and in CH ₂ Cl ₂ .

MHT CET Medical 2026 Solution View → 8

The oxidation process involves

MHT CET Medical 2026 Solution View → 9

The oxidation number of nitrogen in ammonia ( NH ₃ ) is:

MHT CET Medical 2026 Solution View → 10

What is the change in oxidation number of S in the following reaction? SO ₂ + 2 H ₂ S 3 S + 2 H ₂ O

MHT CET Medical 2026 Solution View → 11

Identify the gas that readily decolourises acidified KMnO ₄ solution.

MHT CET Medical 2026 Solution View → 12

Find the average oxidation number of sulphur in tetrathionate ion.

MHT CET Medical 2026 Solution View → 13

Assertion : KMnO ₄, KClO ₄ , and HNO ₃ act as oxidants. Reason : In KMnO ₄, KClO ₄ and HNO ₃ central atom is in its highest oxidation state.

AIIMS 2019 Solution View → 14

BrO ₃⁻ changes into Br ₂ in an acidic medium of a unbalanced equation. How many electron should be present on the balanced equation?

JIPMER 2019 Solution View → 15

When CH ₃ COOCH ₃+ HCl is titrated with NaOH then at neutral point the colour of phenolphthalein becomes colourless from pink due to

AIIMS 2018 Solution View → 16

Which of the following is disproportionation reaction?

JIPMER 2018 Solution View → 17

When hydrogen peroxide is added to acidified solution of dichromate Cr ₂ O ₇²⁻ , a deep blue coloured complex of chromic peroxide CrO ₅ is formed. Oxidation state of Cr in CrO ₅ is

JIPMER 2018 Solution View → 18

Assertion: Equivalent weight of NH ₃ in the reaction, N ₂ NH ₃ is 17 / 3 while that of N ₂ is 28/6. Reason : Equivalent weight = Molecular weight array c Number of e⁻ lost or gaine

AIIMS 2017 Solution View → 19

How many Faradays are required to reduce 1 mol of BrO ₃⁻ to Br ⁻ .

JIPMER 2017 Solution View → 20

Substances that are oxidised and reduced in the following reaction are respectively N ₂ H _ 4(l) +2 H ₂ O _ 2(l) N _ 2(g) +4 H ₂ O _ (l)

AIIMS 2016 Solution View → 21

Which of the following can be oxidised by SO ₂ ?

AIIMS 2016 Solution View → 22

For which of the following elements it is difficult to disproportionate in +3 oxidation state?

AIIMS 2016 Solution View → 23

What is the oxidation number of Br in KBrO ₄ ?

AIIMS 2014 Solution View → 24

Assertion: The correct order of oxidising power is : VO ₂⁺ < Cr ₂ O ₇²⁻ < MnO ₄⁻ Reason: The oxidation state of Mn is +7 .

AIIMS 2014 Solution View → 25

Which will not form precipitation after addition of ( NH ₄ )₂ CO ₃ in presence of NH ₄ Cl ?

AIIMS 2012 Solution View → 26

Predict the product of reaction of I ₂ with H ₂ O ₂ in basic medium.

AIIMS 2011 Solution View → 27

Assertion : Sulphur is oxidised by H ₂ O ₂ in presence of Fe (III). Reason : Fe (III) oxidises sulphur to sulphate.

AIIMS 2011 Solution View → 28

Assertion : Chlorine undergoes disproportionation reaction in alkaline medium. Reason : Cl ₂ is an oxidising agent.

AIIMS 2011 Solution View → 29

Assertion : In an acid-base titration involving strong base and a weak acid, methyl orange can be used as an indicator. Reason : Methyl orange changes its colour in pH range of 7 t

AIIMS 2009 Solution View → 30

2.5 ~g of the carbonate of a metal was treated with 100 ~mL of 1 ~N H ₂ SO ₄ . After the completion of the reaction, the solution was boiled off to expel CO ₂ and was then titrated

AIIMS 2009 Solution View → 31

Assertion : In the iodometric titration starch is used as an indicator. Reason : Starch is a polysaccharide.

AIIMS 2006 Solution View → 32

In the balanced chemical reaction IO ₃⁻+a I ⁻+b H ⁺ c H ₂ O +d I ₂ a, b, c and d respectively corresponds to

AIIMS 2005 Solution View → 33

Oxidation state of Fe in Fe ₃ O ₄ is

AIIMS 2002 Solution View → 34

Assertion : In some cases oxygen shows positive oxidation number though it is an electronegative element. Reason : Fluorine is more electronegative than oxygen.

AIIMS 2001 Solution View → 35

Which element in the reaction of hydrogen peroxide (H 2 O 2 ) undergoes a change from an oxidation state of -1 to 0?

NEET Solution View → 36

In which type of titration is K 2 Cr 2 O 7 used as a self-indicator?

NEET Solution View → 37

In the reaction 2 Na(s) + H 2 (g) → 2 NaH(s), which element undergoes oxidation?

NEET Solution View → 38

What is the purpose of thiosulfate ions (S 2 O 3 2-) in iodometry?

NEET Solution View → 39

Why does iodine remain in solution when KI is present, forming KI 3 ?

NEET Solution View → 40

Which element undergoes a change in oxidation state in this reaction 2 Na(s) + H 2 (g) → 2 NaH (s)?

NEET Solution View → 41

In the half-reaction method for balancing chemical equations, what is added to balance O atoms in reactions occurring in acidic medium?

NEET Solution View → 42

What is the process called when a species loses electrons?

NEET Solution View → 43

In which form is Hg 2 (I)Cl 2 compared to Hg(II)Cl 2 ?

NEET Solution View → 44

Which of the following is NOT a half reaction?

NEET Solution View → 45

What is the term used to describe chemical reactions where oxidation and reduction occur simultaneously?

NEET Solution View → 46

What is the purpose of using an indicator substance in a titration involving K 2 Cr 2 O 7 ?

NEET Solution View → 47

Which substance is oxidized by K 2 Cr 2 O 7 to produce a dramatic blue color change?

NEET Solution View → 48

Which chemical reaction involves the removal of electronegative element chlorine from ferric chloride?

NEET Solution View → 49

What is the chemical symbol for an oxidizing agent in a redox reaction?

NEET Solution View → 50

What is the term "oxidation" defined as in chemistry?

NEET Solution View → 51

What does K 2 Cr 2 O 7 oxidize in the presence of diphenylamine to produce a blue color?

NEET Solution View → 52

Which element is commonly used as an oxidizing agent in the extraction of metals from their ores?

NEET Solution View → 53

In which type of solution is the addition of OH- ions necessary to balance ionic charges in a redox reaction?

NEET Solution View → 54

What is the net balanced equation for the given redox reaction after canceling electrons on both sides?

NEET Solution View → 55

Which of the following is an example of a reducing agent?

NEET Solution View → 56

How many moles of electrons are transferred when 4 moles of sodium (Na) react completely 2 Na(s) + H 2 (g) → 2 NaH (s) ?

NEET Solution View → 57

What happens to the oxidation state of an element when it acts as a reducing agent?

NEET Solution View → 58

What type of chemical reaction involves the transfer of electrons from a reducing agent to an oxidizing agent?

NEET Solution View → 59

In the reaction 2H 2 (g) + O 2 (g) → 2H 2 O(l), which element goes from a neutral (zero) state to a positive state?

NEET Solution View → 60

What is the oxidation number of hydrogen when it is bonded to metals in binary compounds?

NEET Solution View → 61

In the reaction 2H 2 (g) + O 2 (g) → 2H 2 O(l), what is the oxidation state of oxygen in H 2 O?

NEET Solution View → 62

What is the purpose of adding H+ ions in a redox reaction carried out in acidic solution?

NEET Solution View → 63

What is the color of K 2 Cr 2 O 7 before it undergoes reduction in a titration?

NEET Solution View → 64

What is the purpose of stoichiometric calculations in iodometry?

NEET Solution View → 65

What is the term used to describe the assumption of a complete transfer of electrons from a less electronegative atom to a more electronegative atom in chemical reactions?

NEET Solution View → 66

What is the oxidation number of oxygen in superoxides?

NEET Solution View → 67

What is the term used for the substance that causes oxidation in a redox reaction?

NEET Solution View → 68

Which group in the periodic table exhibits the highest oxidation number equal to the group number?

NEET Solution View → 69

Which term is used interchangeably with "oxidizing agent" and refers to a substance that accepts electrons in a chemical reaction?

NEET Solution View → 70

What is the oxidizing agent in the given reaction, 2 Na (s) + H 2 (g) → 2 NaH (s)?

NEET Solution View → 71

How is the oxidation number expressed in Stock notation?

NEET Solution View → 72

Which element is oxidized in the reaction: 2 H 2 S(g) + O 2 (g) → 2 S (s) + 2 H 2 O (l)?

NEET Solution View → 73

In a basic medium, what is added to the equation to balance each H+ ion?

NEET Solution View → 74

In the oxidation number method for balancing redox reactions, what is the first step?

NEET Solution View → 75

In which type of solution should OH- ions be added to balance ionic charges in a redox reaction?

NEET Solution View → 76

When is the equation for a redox reaction considered balanced?

NEET Solution View → 77

Which of the following is NOT a characteristic of an oxidizing agent?

NEET Solution View → 78

What is the product of the oxidation half-reaction in the given redox reaction involving MnO4- and I-?

NEET Solution View → 79

What is the oxidation number of magnesium in Mg2+ ions?

NEET Solution View → 80

In the reaction CH 4 (g) + 4Cl 2 (g) → CCl 4 (l) + 4HCl(g), which element undergoes oxidation?

NEET Solution View → 81

In which type of reaction does an oxidizing agent gain electrons?

NEET Solution View → 82

Which compound is represented as Au(I)Cl in Stock notation?

NEET Solution View → 83

What is the oxidation number of oxygen in peroxides?

NEET Solution View → 84

Which of the following is NOT considered an example of oxidation?

NEET Solution View → 85

Which reaction represents the addition of hydrogen to a substance?

NEET Solution View → 86

What is the term for the method used to balance redox reactions based on assigning oxidation numbers?

NEET Solution View → 87

Which reagent is responsible for giving an intense blue color with starch in the method of Iodometry?

NEET Solution View → 88

Which element's oxidation number depends on its bonding state when bonded to fluorine?

NEET Solution View → 89

What should be done if the increase or decrease in oxidation number per atom and for the entire molecule/ion is not equal in a redox reaction?

NEET Solution View → 90

In the oxidation number method, what is the significance of identifying atoms that undergo a change in oxidation number?

NEET Solution View → 91

Which element is reduced in the reaction 2Na(s) + Cl 2 (g) → 2NaCl(s)?

NEET Solution View → 92

What does the oxidation number denote in a compound?

NEET Solution View → 93

What is the oxidation state of oxygen in O 2 in the reaction 2H 2 (g) + O 2 (g) → 2H 2 O(l)?

NEET Solution View → 94

What is the purpose of an indicator substance in titrations where there is no self-color change?

NEET Solution View → 95

What type of titration involves the use of K 2 Cr 2 O 7 as an oxidizing agent?

NEET Solution View → 96

Which of the following substances is commonly used as an oxidizing agent in laboratory experiments and is known for its strong oxidizing properties?

NEET Solution View → 97

In the reaction 2Na(s) + Cl 2 (g) → 2NaCl(s), what is sodium's role?

NEET Solution View → 98

In the reaction CH 4 (g) + 4Cl 2 (g) → CCl 4 (l) + 4HCl(g), which element undergoes a reduction?

NEET Solution View → 99

Which notation is used to express the oxidation number of a metal in a compound, as described by Alfred Stock?

NEET Solution View → 100

What is the oxidation number of iron in Fe3+ ions?

NEET Solution View → 101

Which of the following is an example of an oxidizing agent used in bleaching and disinfection?

NEET Solution View → 102

What is the change in oxidation state of sodium (Na) in this reaction 2 Na(s) + H 2 (g) → 2 NaH (s)?

NEET Solution View → 103

In the oxidation number method, what is done to ensure that the total ionic charges of reactants and products are equal in a redox reaction?

NEET Solution View → 104

In the reduction half-reaction, how many electrons are added to balance the charge when Cr 2 O 7 2- ions are reduced to Cr3+ ions?

NEET Solution View → 105

Which term is synonymous with "reducing agent" in the context of electron transfer reactions?

NEET Solution View → 106

Which of the following elements can exist in at least three oxidation states and undergo disproportionation reactions in an alkaline medium?

NEET Solution View → 107

Which substance is commonly titrated with K 2 Cr 2 O 7 to determine its concentration?

NEET Solution View → 108

What is the process by which a reagent increases the oxidation number of an element in a substance?

NEET Solution View → 109

In the reaction H 2 (s) + Cl 2 (g) → 2HCl(g), what is the oxidation state of chlorine in HCl?

NEET Solution View → 110

What is the product of the disproportionation reaction of hydrogen peroxide (H 2 O 2 )?

NEET Solution View → 111

What is the purpose of adding starch to the solution during iodometry using Cu(II) as the oxidizing agent?

NEET Solution View → 112

Which ion is reduced by K 2 Cr 2 O 7 during a titration?

NEET Solution View → 113

What is the term used for the substance that causes reduction in a redox reaction?

NEET Solution View → 114

What is the oxidation number of fluorine in its compounds?

NEET Solution View → 115

What should be added to a redox reaction equation in water to balance ionic charges if it's carried out in a neutral solution?

NEET Solution View → 116

What is the role of K 2 Cr 2 O 7 when it is not a self-indicator in a titration?

NEET Solution View → 117

In the oxidation half-reaction, what is the product when Fe2+ ions are oxidized to Fe3+ ions?

NEET Solution View → 118

Which compound is better written as (Na+)2S2-(s)?

NEET Solution View → 119

What type of reaction occurs when hydrogen combines with oxygen to form water?

NEET Solution View → 120

What does the oxidation state of an element in a compound represent?

NEET Solution View →
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