Redox Reactions PYQs Set 2 (PDF)

Set 2 of 6 · Questions 31-60 of 163

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Redox Reactions · Set 2 (Q31-60)
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31. $Common oxidation state of f -block elements is III. The other stable oxidation states of^{63} Eu and^{65} Tb are respectively$ (1) $II, IV$ (2) $IV, II$ (3) $II, V$ (4) $V, II$ 32. $Oxidation numbers of P in P O_{4}^{3 -}, of S in S O_{4}^{2 -} and that of Cr in C r_{2} O_{7}^{2 -} are respectively$ (1) $+ 3, + 6 and + 5$ (2) $+ 5, + 3 and + 6$ (3) $- 3, + 6 and + 6$ (4) $+ 5, + 6 and + 6$ 33. $Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Phenolphthalein is a pH dependent indicator, remains colourless in acidic solution and gives pink colour in basic medium Reason R : Phenolphthalein is a weak acid. It doesn't dissociate in basic medium. In the light of the above statements, choose the most appropriate answer from the options given below:$ (1) $Both A and R are true and R is the correct explanation of A$ (2) $Both A and R are true but R is NOT the correct explanation of A.$ (3) $A is true but R is false$ (4) $A is false but R is true$ 34. $Given below are two statements: Statement I: In redox titration, the indicators used are sensitive to change in Ph of the solution. Statement II: In acid-base titration, the indicators used are sensitive to change in oxidation potential. In the light of the above statements, choose the most appropriate answer from the options given below$ (1) $Statement I is correct but Statement II is incorrect$ (2) $Both Statement I and Statement II are incorrect$ (3) $Statement I is incorrect but Statement II is correct$ (4) $Both Statement I and Statement II are correct$ 35. $Which among the following species does not shown disproportionation reaction?$ (1) $ClO^{-}$ (2) $ClO_{2}^{-}$ (3) $ClO_{3}^{-}$ (4) $ClO_{4}^{-}$ 36. $Which of the following cannot function as an oxidising agent?$ (1) $N^{3 -}$ (2) $SO_{4}^{2 -}$ (3) $BrO_{3}^{-}$ (4) $MnO_{4}^{-}$ 37. $Observe the following reaction a P_{4} (s) + b^{-} OH (aq) + H_{2} O (1) \to cPH_{3} (g) + d H_{2} PO_{2}^{-} (aq) a, b, c and d are respectively$ (1) $1, 3, 3, 1$ (2) $1, 3, 2, 3$ (3) $3, 1, 3, 1$ (4) $1, 3, 1, 3$ 38. $During the reaction of permanganate with thiosulphate, the change in oxidation of manganese occurs by value of 3. Identify which of the below medium will favour the reaction.$ (1) $Both aqueous acidic and neutral$ (2) $Aqueous neutral$ (3) $Both aqueous acidic and faintly alkaline$ (4) $Aqueous acidic$ 39. $Given below are two statements : Statement (I) : Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution. Statement (II) : In this titration phenolphthalein can be used as indicator. In the light of the above statements, choose the most appropriate answer from the options given below:$ (1) $Both Statement I and Statement II are correct$ (2) $Statement I is correct but Statement II is incorrect$ (3) $Statement I is incorrect but Statement II is correct$ (4) $Both Statement I and Statement II are incorrect$ 40. $The oxide, which cannot act as a reducing agent is$ (1) $C O_{2}$ (2) $C l O_{2}$ (3) $N O_{2}$ (4) $S O_{2}$ 41. $Observe the following reaction xS_{8} (s) + yOH^{-} (aq) \to zS^{2 -} (aq) + 2 S_{2} O_{3}^{2 -} (aq) + 6 H_{2} O (l) x, y and z are respectively.$ (1) $1, 12, 4$ (2) $1, 12, 2$ (3) $1, 4, 12$ (4) $2, 12, 2$ 42. $In the reaction, MnO_{4 (aq)}^{-} + Br_{(aq)}^{-} ⟶ MnO_{2 (s)} + BrO_{3 (aq)}^{-}, the correct change in oxidation number of the species involved is$ (1) $Br^{+ 5} to Br^{- 1}$ (2) $Mn^{+ 7} to Mn^{+ 2}$ (3) $Mn^{+ 7} to Mn^{+ 3}$ (4) $Br^{- 1} to Br^{+ 5}$ 43. $Which of the following reactions is the metal displacement reaction? Choose the right option.$ (1) $Cr_{2} O_{3} + 2 Al \to ∆ Al_{2} O_{3} + 2 C r$ (2) $Fe + 2 HCl ⟶ FeCl_{2} + H_{2} ↑$ (3) $2 Pb (NO_{3})_{2} ⟶ 2 PbO + 4 NO_{2} + O_{2} ↑$ (4) $2 KClO_{3} \to ∆ 2 KCl + 3 O_{2}$ 44. $The number of elements among O, Cl, F, N, P, Sn, Ti, K, Sc, which show more than one non-zero oxidation state is$ (1) $2$ (2) $3$ (3) $6$ (4) $8$ 45. $For the redox reaction, x MnO_{4}^{-} + y H_{2} C_{2} O_{4} + z H^{+} \to m Mn^{2 +} + n CO_{2} + p H_{2} O The values of x, y, m and n are$ (1) $10, 2, 5, 2$ (2) $2, 5, 2, 10$ (3) $6, 4, 2, 4$ (4) $3, 5, 2, 10$ 46. $What is the oxidation state of Mn in MnO_{4}^{-} ?$ (1) $+5$ (2) $+6$ (3) $+4$ (4) $+7$ 47. $The oxidation states of three carbon atoms in carbon suboxide (C_{3} O_{2}) respectively are$ (1) $+ 2, 0, + 2$ (2) $+ 2, 0, + 4$ (3) $+ 4, + 2, + 2$ (4) $- 2, + 2, 0$ 48. $Given below are two statements: Statement I: S_{8} solid undergoes disproportionation reaction under alkaline conditions to form S^{2 -} and S_{2} O_{3}^{2 -} Statement II: ClO_{4}^{-} can undergo disproportionation reaction under acidic condition. In the light of the above statements, choose the most appropriate answer from the options given below :$ (1) $Statement I is correct but statement II is incorrect.$ (2) $Statement I is incorrect but statement II is correct$ (3) $Both statement I and statement II are incorrect$ (4) $Both statement I and statement II are correct$ 49. $The oxidation number of nitrogen atoms in NH_{4} NO_{3} are$ (1) $- 3, + 5$ (2) $+ 3, - 5$ (3) $- 3, - 3$ (4) $+ 5, + 5$ 50. $In neutral or faintly alkaline medium, MnO_{4}^{-} oxidizes I^{-} to iodate. What is the number of moles of KMnO_{4} required to completely convert 1 L of 0.5 MKI to iodate?$ (1) $0.5$ (2) $4.0$ (3) $2.0$ (4) $1.0$ 51. $Which of the following is not a disproportionation reaction?$ (1) $Cl_{2} (g) + 2 OH^{-} (aq) \to ClO^{-} (aq) + Cl^{-} (aq) + H_{2} O$ (2) $F_{2} (g) + 2 OH^{-} (aq) \to OF_{2} (g) + 2 F^{-} (aq) + H_{2} O (l)$ (3) $4 ClO_{3}^{-} (aq) \to Cl^{-} (aq) + 3 ClO_{4}^{-} (aq)$ (4) $3 ClO^{-} (aq) \to 2 Cl^{-} (aq) + ClO_{3}^{-} (aq)$ 52. $The volume, in mL, of 0.02 MK_{2} Cr_{2} O_{7} solution required to react with 0.288 g of ferrous oxalate inacidic medium is(Molar mass of Fe = 56 gmol^{- 1})$ 53. $20 mL of calcium hydroxide was consumed when it was reacted with 10 mL of unknown solution of H_{2} S O_{4} . Also 20 mL standard solution of 0.5 M HC1 containing 2 drops of phenolphthalein was titrated with calcium hydroxide, the mixture showed pink colour when burette displayed the value of 35. 5 mL whereas the burette showed 25.5 mL initially. The concentration of H_{2} S O_{4} is_______M. (Nearest integer)$ 54. $10.0mL of 0.05 M K M n O_{4} solution was consumed in a titration with 10.0mL of given oxalic acid dihydrate solution. The strength of given oxalic acid solution is \dots. \times 1 0^{- 2} g / L . (Round off to the nearest integer)$ 55. $X and Y are the number of electrons involved, respectively during the oxidation of I^{-} to I_{2} and S^{2 -} to S by acidified K_{2} Cr_{2} O_{7} . The value of X + Y is____.$ 56. $If 50 mL of 0.5 M oxalic acid is required to neutralise 25 mL of NaOH solution, the amount of NaOH in 50 mL of given NaOH solution is ____g.$ 57. $K M n O_{4} is titrated with ferrous ammonium sulphate hexahydrate in presence of dilute H_{2} S O_{4} . Number of water molecules produced for 2 molecules of K M n O_{4} is________$ 58. $200 cc of x \times 10^{- 3} M potassium dichromate is required to oxidise 750 cc of 0.6 M Mohr's salt solution in acidic medium. Here x =____.$ 59. $2L of 0.2 M H_{2} S O_{4} is reacted with 2L of 0.1 M NaOH solution, the molarity of the resulting product N a_{2} S O_{4} in the solution is____millimolar.(Nearest integer).$ 60. $The volume (in mL) of 0.1 NNaOH required to neutralise 10 mL of 0.1 N phosphinic acid is$