Please refer to Chapter 8 Redox Reactions MCQ Class 11 Chemistry with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 11 Chemistry. Students should refer to MCQ Questions for Class 11 Chemistry with Answers to score more marks in Grade 11 Chemistry exams. Students should read the chapter Redox Reactions and then attempt the following objective questions.

MCQ Questions Class 11 Chemistry Chapter 8 Redox Reactions

The Redox Reactions MCQ Class 11 Chemistry provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. The ratio of oxidation states of Cl in potassium chloride to that in potassium chlorate is 
(a) + 1/5
(b) -1/5
(c) – 2/5
(d) + 3/ 5     

Question. In the reaction, 8AI + 3Fe₃O₄ → 4AI₂O₃ + 9Fe the number of electrons transferred from the reductant to the oxidant is 
(a) 8
(b) 4
(c) 16
(d) 24         

Question. If CI₂ is passed through hot aqueous NaOH, the products formed have Cl in different oxidation states. These are indicated as 
(a) – land + 1
(b) – land + 5
(c) + land + 5
(d) – land + 3     

Question. In the redox reaction,
MnO⁺⁷₄ + 8H⁺ + 5Br^– → Mn²⁺ + 4H₂O + 5/2 Br₂
Which one is the reducing agent?
(a) H⁺
(b) MnO^–₄
(c) Br^–
(d) Mn²⁺     

Question. The oxidation number and the electronic configw-ation of sulphur in H₂SO₄ is 
(a) + 4; 1s² ,2s² ,2p⁶ ,3s²
(b) + 2; 1s² ,2s² ,2p⁶ ,3s² ,3p²
(c) + 3; 1s² ,2s² ,2p⁶ ,3s² ,3p¹
(d) + 6; 1s² ,2s² ,2p⁶       

Question. Oxidation state of oxygen in H₂O₂ is 
(a) – 1
(d) – 2
(c) 1/ 2
(b) + 2           

Question. Which one of the following oxidation states is not possible in metal carbonyls?
(a) +1
(b)  0
(c) – 1
(d) +2     

Question. The oxidation state and covalency of Al in [AlCI (H₂O)₅]²⁺ respectively are 
(a) +6,6
(b) +3,6
(c) +2,6
(d) +3,3   

Question. What is the oxidation number of Pt in K [Pt NH₃Cl₅] ?
(a) 0
(b) + 1 
(c) + 2
(d) + 4     

Question. The pem1anganate ion is an excellent oxidising agent in aqueous solutions. When the half-reaction,
MnO₄ + H⁺ + e^– → MnO₂ + H₂O is balanced, the correct coefficients for the species involved are
(a) 1,4,4, 1,2
(b) 1,4,2,1,2
(c) 1,4, 3, 1, 2
(d) 1,4, 1, 1, 2   

Question. A reagent which lowers the oxidation number of an element in a given substance is known as 
(a) oxidising agent
(b) reduction
(c) reducing agent
(d) oxidation       

Question. In Br₃O₈ compound, oxidation number of bromine is
(a) 16/13
(b) 26/3
(c) 24/3
(d) 16/3       

Question. Consider the following reaction,
xMnO^–₄ + yC₂O^2-₄ + zH⁺ → xMn²⁺
                                         + 2yCO₂ + z/2 H₂O,
The value of x, y and z in the reaction respectively are
(a) 5, 2 and 16
(c) 2, 5 and 16
(b) 2, 5 and 8 
(d)5, 2and 8   

Question. Hydrogen peroxide in its reaction with KIO₄ and NH₂OH respectively, is acting as a 
(a) reducing agent, oxidising agent
(b) reducing agent, reducing agent
(c) oxidising agent, oxidising agent
(d) oxidising agent, reducing agent 

Question. State the oxidation number of carbonyl carbon in methanal and methanoic acid, respectively 
(a) 0 and 0
(b) 0 and + 2
(c) + I and + 2
(d) + I and + 3     

Question. Which order of compounds in according to the decreasing order of the oxidation state of nitrogen? 
(a) HNO₃ , NO, NH₄Cl, N₂
(b)  HNO₃ , NO, N₂ ,NH₄Cl
(c)  HNO₃ , NO, NH₄Cl, N₂
(d)  HNO₃ , NH₄Cl, N₂ ,NO     

Question. For the reaction, NH₃ + OCI^– → N₂H₄ + Cl^– occurring in basic medium, the coefficient of N₂H₄ in the balanced equation will be
(a) 1
(b) 2
(c) 3
(d) 4       

Question. In which of the following reactions, H₂O₂ acts as a reducing agent?
I. H₂O₂ + 2H⁺ + 2e^– → 2H₂O
II. H₂O₂ – 2e^–– → O₂ + 2H⁺
III. H₂O₂ – 2e^–– → O₂ + 2H
IV. H₂O₂ + 2H⁺ + 2e^– → O₂ + 2H₂O
(a) I and II
(b) III and IV
(c) I and III
(d) II and III   

Question. Reaction of Br₂ with Na₂CO₃ in aqueous solution gives sodium bromide and sodium bromate with evolution of CO₂ gas. The number of sodium bromide molecules involved in the balanced chemical equation is 
(a) 1
(b) 3
(c) 5
(d) 7     

Question. In which of the following, oxidation number of chlorine is + 5 ?
(a) Cl^–
(b) CIO^–
(c) ClO^–₂
(d) ClO^–₃       

Question. The coefficients of I^– , IO^–₃ and H⁺ in the redox reaction,
             I^– + IO^–₃ + H⁺ → I₂ + H₂O
in the balanced form, respectively are 
(a) 5 ,1 ,6
(b) 1 ,5 ,6
(c) 6 ,1 ,5
(d) 5 ,6 ,1     

Question. ln the reaction, H₂S + H₂O₂ → S + 2H₂O
(a) H₂S is an acid and H₂O₂ is a base 
(b) H₂ Sis a base and H₂O₂ is an acid
(c) H₂S is an oxidising agent and H₂O₂ is a reducing agent
(d) H₂S is a reducing agent and H₂O₂ is an oxidising agent   

Question. Which quantities are conserved in all redox reactions?
(a) Charge only 
(b) Mass only
(c) Both charge and mass
(d) Neither charge nor mass   

Question. ln which of the following reactions, chlorine acts as an oxidising agent ?
I. CH₃CH₂OH + Cl₂ → CH₃CHO + HCI
II. CH₃CHO + Cl₂ → CCl₃ ·CHO + HCI
III. CH₄ + Cl₂ → CH₃Cl + HCI
The correct answer is
(a) Only I
(b) Only II
(c) I and III
(d) I, II and III     

Question. The oxidation number of sulphur in H₂S₂O₈ is 
(a) + 2
(b) +4
(c) +6
(d) + 7       

Question. For the reaction, I^– + ClO^–₃ + H₂SO₄ → CI^– + HSO^–₄ + I₂ The correct statement(s) in the balanced equation is/are
(a) stoichiometric coefficient of HSO^–₄ is 6
(b) iodide is oxidised
(c) sulphur is reduced
(d) H₂O is one of the products   

Question. The difference in the oxidation numbers of the two types of sulphur atoms in Na₂S₄O₆ is 
(a) 4
(b) 5
(c) 6
(d) 7       

Question. Oxidation states of the metal in the minerals haematite and magnetite, respectively, are 
(a) II, III in haematite and III in magnetite
(b) II, III in haematite and II in magnetite
(c) II in haematite and II, III in magnetite
(d) III in haematite and II, min magnetite     

Question. When sulphur dioxide is passed in an acidified K₂Cr₂O₇ solution, the oxidation state of sulphur is changed from
(a) + 4 to 0
(b) + 4 to + 2 
(c) + 4 to + 6
(d) + 6 to + 4     

Question. Ceric ammonium sulphate and potassimn permanganate are used as oxidising agents in acidic medium for oxidation offenous ammonium sulphate to ferric sulphate. The ratio of number of moles of eerie ammonium sulphate required per mole of ferrous ammonium sulphate to the number of moles of KMnO₄ required per mole offerrous ammonium sulphate, is 
(a) 5.0
(b) 0.2
(c) 0.6
(d) 2.0       

Question. Out of the following redox reactions,
I. NH₄NO₃ →^Δ N₂O + 2H₂O
II. NH₄NO₂ →^Δ N₂ + 2H₂O
III. PCl₅ →^Δ PCl₃ + CI₂
disproportionation is not shown in 
(a) I and II
(b) II and III
(c) I and III
(d) I, II and III     

Question. Which of the following species contain an element in an oxidation state that is not a whole number? 
(a) VO^3-₄
(b) Mn₂O₃
(c) S₄O^2-₆
(d) Cl₂O₇     

Question. In the following reaction,
M^x+ + MnO^–₄ → MO^–₃ + Mn²⁺ + 1/2 O₂,
If one mole of MnO^–₄ oxidises 2.5 moles of M^x+ then the value of xis
(a) 5
(b) 3
(c) 4
(d) 2       

Question. In acidic medium, Zn reduces nitrate ion to NH^–₄ ion according to the reaction,
Zn + NO^–₃ → Zn²⁺ + NH⁺₄ + H₂O (unbalanced) How many moles of HCl are required to reduce half a mole of NaNO₃ completely? Assume the availability of sufficient Zn. 
(a) 5
(b) 4
(c) 3
(d) 2     

Question. Among NH₃ , HNO₃ , NaN₃ and Mg₃N₂; the number of molecules having nitrogen in negative oxidation state is 
(a) 1
(b) 2 
(c) 3
(d) 4       

Question. In the equation, CrO^2-₄ + SO^2-₃ → Cr(OH)^–₄ + SO^2-₄ the oxidation number of Cr changes from 
(a) + 6 to + 4
(b) + 6 to + 3
(c) + 8 to + 4
(d) + 4 to + 3   

Question. Which of the following reaction involves oxidation and reduction ? 
(a) NaBr + HCl → NaCl + HBr
(b) HBr + AgNO₃ → AgBr + HNO₃
(c) H₂ + Br₂ → 2HBr
(d) Na₂O + H₂SO₄ → Na₂SO₄ + H₂O     

Question. What is the oxidation state of Pin Ba(H₂PO₂)₂ h?
(a) + 1
(b) + 2
(c) + 3
(d) – 1     

Question. Which one of the following reactions involves disproportionation ? 
(a) 2H₂SO₄ + Cu → CuSO₄ + 2H₂O + SO₂
(b) As₂O₃ + 3H₂S → As₂S₃ + 3H₂O
(c) 2KOH + CI₂ → KCI + KOCI + H₂O
(d) Ca₃P₂ + 6H₂O → 3Ca(OH)₂ + 2PH₃     

Question. In which of the following, the oxidation number of oxygen has been arranged in increasing order ? 
(a) OF₂ < KO₂ < BaO₂ < O₃
(b) BaO₂ < KO₂ < O₃ < OF₂
(c) BaO₂ < O₃ < OF₂ < KO₂
(d) KO₂ < OF₂ < O₃ < BaO₂     

Question. The oxidation state of sulphur in sodium tetrathionate (Na₂S₄O₆ )is
(a) 2
(b) 0
(c) 2.5
(d) 3.5       

Question. During a redox titration involving a solution containing Fe²⁺ ions against MnO^–₄ in the presence of excess of H⁺ ions, the number of electrons that gets transferred is
(a) 6
(b) 5 
(c) 4
(d) 2       

Question. The oxidation state of Cr in chromium trioxide is
(a) + 3
(c) + 5
(b) + 4
(d) + 6       

Question. The oxidation number of chromium in potassium dichromate is 
(a)+ 2
(c) + 6
(b) + 4
(d) + 8       

Question. The oxidation states of iodine in HIO₄ , H₃IO₅ and H₅IO₆ respectively, are 
(a) + 1, + 3, + 7
(b) + 7, + 7, + 3
(c) + 7, + 7, + 7
(d) + 7, + 5, + 3       

Question. In the ionic equation,
BiO^–₃ + 6H⁺ +xe^– → Bi³⁺ + 3H₂O
the value of x is 
(a) 6
(b) 2
(c) 4
(d) 3         

Question. Oxidation number of sulphur in Caro’s acid is 
(a) + 6
(b) + 4
(c) + 8
(d) + 7       

Question. Which of the following chemical reactions depicts the oxidising behaviour of H₂SO₄ ? 
(a) 2HI + H₂SO₄ → I₂ + SO₂ + 2H₂O
(b) Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O
(c) NaCl+ H₂SO₄ → NaHSO₄ + HCI
(d) 2PCI₅ + H₂SO₄ → 2POCl₃ + 2HCI + SO₂Cl₂     

Question. The oxidation number of xenon in XeOF₂ is 
(a) zero
(b) + 2
(c) + 4
(d) + 3     

Question. The number of moles of KMnO₄ reduced by one mole of Kl in alkaline medium is 
(a) 1
(b) 5
(c) 1/2
(d) 1/5       

Question. The oxidation number of oxygen in KO₃ , Na₂O₂ is
(a) 3, 2
(b) 1, 0 
(c) 0, 1
(d) – 0.33, -1       

Question. The value of ‘n’ in the reaction,
Cr₂O^2-₇ + 14H⁺ + nFe²⁺ → 2Cr³⁺ + nFe³⁺ + 7H₂O
will be
(a) 2
(b) 3
(c) 6
(d) 7     

Question. When K₂Cr₂O₇ is converted into K₂CrO₄ , the change in oxidation number of chromium is 
(a) 0
(b) 5
(c) 7
(d) 9       

Question. One mole of acidified K₂Cr₂O₇ on reaction with excess Kl will liberate ……. mole(s) of I₂ . 
(a) 6
(b) 1
(c) 7
(d) 2     

Question. Which is the best description of behaviour of bromine in the reaction given below ?
              H₂O + Br₂ → HBr + HOBr 
(a) Proton acceptor only
(b) Both oxidised and reduced
(c) Oxidised only
(d) Reduced only     

Question. Oxidation numberof S in sot 
(a) +6
(b) +3
(c) + 2
(d) – 2     

Question. Which one of the following is a redox reaction?
(a) NaCl + KNO₃ → NaNO₃ + KCl
(b) CaC₂O₄ + 2HCI → CaCI₂ + H₂C₂O₄
(c) Ca(OH)₂ + 2NH₄CI → CaCI₂ + 2NH₃ + 2H₂O
(d) 2K[Ag(CN)₂] + Zn → 2Ag + K₂ [Zn(CN)₄ ]     

Question. In which of the following compounds, the oxidation nwnber of iodine is fractional ? 
(a) IF₃
(b) IF₅
(c) I^–₃
(d) IF₇     

Question. Oxidation state of sulphur in Na₂S₂O₃ and Na₂S₄O₆
(a) 4 and 6
(b) 3 and 5 
(c) 2 and 2.5
(d) 6 and 6       

Question. Which one of the following reaction is possible at anode?
(a) F₂ + 2e^– → 2F^– 
(b) 2H⁺ + 1/2 O₂ +2e^– → H₂O
(c) 2Cr³⁺ + 7H₂O → Cr₂O^2-₇ + 14H⁺ + 6e^–
(d) Fe²⁺ → Fe³⁺ + e^–     

Question. Oxidation number of N in N₃ H (hydrazoic acid) is
(a) -1 / 3
(c) 0
(b) + 3
(d) – 3     

Question. The oxidation state of l in IPO₄ is
(a) + 1
(b) + 3
(c) + 5
(d) + 7   

Question. Which of the following acts as an oxidising as well as reducing agent ? 
(a) Na₂O
(b) Na₂O₂
(c) NaNO₃
(d) NaNO₂       

Question. The reaction,
P₄ + 3NaOH + 3H₂O → 3NaH₂PO₂ + PH₃
is an example of 
(a) disproportionation reaction
(b) neutralisation reaction
(c) double-decomposition reaction
(d) pyrolytic reaction       

Question. The oxidation state of Fe in Fe₃O₄ is
(a) + 3
(b) 8/3
(c) + 6
(d) + 2     

Question. In the reaction, SO₂ + 2H₂S → 3S + 2H₂O, the substance oxidised is
(a) H₂S
(b) SO₂
(c) S
(d) H₂O       

Question. Mno; is a good oxidising agent in different medium changing to 
MnO^–₄ ➔ Mn²⁺ ➔ MnO^2-₄ ➔ MnO₂ ➔ Mn₂O₃ Changes in oxidation number respectively are
(a) 1 ,3 ,4 ,5 
(b) 5 ,4 ,3 ,2
(c) 5 ,1 ,3 ,4
(d) 2 ,6 ,4 ,3     

Question. In the conversion of Br₂ to BrO^–₃, the oxidation number of Br changes from 
(a) zeroto + 5
(b) +lto+5
(c) zero to – 3
(d) + 2 to + 5       

Question. Oxidation states of X, Y, Z are + 2, + 5 and -2 respectively. Formula of the compound formed by these will be 
(a) X 2yz₆
(b) XY₂Z₆
(c) XY₅
(d) X₃YZ₄         

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