Tiêu đề Redox Reaction - 01.pdf ✅

1 JEE ADVANCED 2024 Redox Reaction Single Correct (1 – 5) 1. In a redox change Ba(MnO4)2 oxidises K4 [Fe(CN)6] into K+ , Fe3+ , CO3 2- and NO3 – ions in acidic medium, it self being reduced to Mn2+ ions. How many moles of Ba(MnO4)2 are reduced by 1 mole of K4 Fe(CN)6? (1) 5.8 (2) 6.1 (3) 7.2 (4) 8.8 2. 0.804 g sample of iron ore was dissolved in acid. Iron was oxidized to +2 state and it required 47.2 mL of 0.112 NKMnO4 solution for titration. Calculate % of Fe and Fe3O4 in ore. (1) 36.8, 50.8 (2) 36.8, 68 (3) 30, 50.8 (4) 30, 68 3. Equivalent mass of Fe3O4 and Fe2O3 in the change Fe3O4 ⟶ Fe2O3 is respectively. M1 and M2 are molar mass of Fe3O4 and Fe2O3 respectively: (1) 2 1 3 , 2 M M (2) 1 2 , 3 2 M M (3) 1 2 , 2 3 M M (4) 2 1 3 , 2 M M 4. A certain amount of a reducing agent reduces x mole of MnO2 and y mole of K2CrO4 in different reactions in acidic medium. If the changes in oxidation states of reducing agent in the reactions are in 1:2 ratio, respectively, then the ratio of x and y is (1) 2:3 (2) 1:3 (3) 3:4 (4) 3:2 5. Dichloroacetic acid (CHCl2CO2H) is oxidized to CO2, H2O and Cl2 by 1.2 equivalents of an oxidizing agent. Same amount of the acid can neutralize ' X ' moles of NH3 to give ammonium dichloroacetate. The value of ' X ' is (1) 0.4 (2) 0.3 (3) 0.2 (4) 0.1 One or more than one correct 6. A metal forms two oxides. The higher oxide contains 20% oxygen, while 4.29 g of the lower oxide when converted to higher oxide, become 4.77 g. The equivalent weight of metal in (1) lower oxide is 32. (2) lower oxide is 64.4. (3) higher oxide is 64.4. (4) higher oxide is 32. 7. The specific heat of a metal is found to be 0.03. 10g of the metal on treatment with nitric acid gave 18.9"g of pure dry nitrate. The correct statement(s) is/are (1) The equivalent weight of the metal is 69.66. (2) The atomic weight of the metal is 209. (3) The metal is trivalent. (4) The metal is an alkali metal. 8. A mixture of Na2C2O4 and H2C2O4 requires 100 mL of 0.1MKMnO4 for complete neutralisation. The same mixture on neutralisation by a base requires 50 mL of 0.2 M NaOH solution. Which one are correct? (1) Mole ratio of Na2C2O4 and H2C2O4 = 4 : 1 (2) Equivalent ratio of Na2C2O4 and H2C2 O4 = 4:1 (3) Mole of C2O4 2– in mixture = 25 × 10–3 (4) Mole ratio of Na2C2O4 and H2C2O4 = 1:4 9. Quantitative estimation of Fe2+ can be made by KMnO4 in acidified medium. In which medium it can be estimated by KMnO4? (1) In2SO4 (2) In HNO3 (3) In HCl (4) All of these 10. Which are correct about the reaction? FeS2 + O2 ⟶ Fe2O3 + SO2 (1) Eq. mass of FeS2 is M/11 (2) Eq. mass of SO2 = M/5 (3) 1 mole of FeS2 requires 7/4 mole of O2 (4) S has -2 oxidation state in FeS2 11. Which of the following are primary standards? (1) As2O3 (2) H2C2O4 (3) NaOH (4) Na2CO3 DPP - 01
2 Comprehension – 1 Estimation of CuSO4 is made by isdometric titrations. In a given titration CuSO4 reacts with KI in acidic medium to liberate I2. 2CuSO4 + 4KI ⟶ Cu2I2 + 2 K2SO4 + I2 Mercuric per iodate Hg5(IO6)2 reacts with a mixture of Kl and HCl following the equation: Hg5 (IO6)2 + 34 KI + 24HCl ⟶ 5 K2 HgI4 + 8I2 + 24KCl + 12H2O The liberated iodine is titrated against Na2 S2O3 solution. One mL of which is equivalent to 0.0499g of CuSO4⋅5H2O. Molar mass of Hg5 (IO6)2 = 1448.5 and molar mass of CaSO4⋅5H2O = 249.5. 12. Equivalent mass of CuSO4⋅5H2O is : (1) M/2 (2) M/1 (3) M/3 (4) M 13. The reaction of Na2 S2O3 and I2 gives oxidation product as: (1) I – (2) S2O3 2- (3) S4O6 2– (4) SO4 2– 14. Volume in mL of Na2S2O3 solution will be required to react with I2 liberated from 0.76245 g of Hg5 (IO6)2: (1) 40 mL (2) 10 mL (3) 20 mL (4) 30 mL Comprehension – 2 K2Cr2O7 acts as a good oxidizing agent in acidic medium. Cr2O7 2− Orange + 14H + + 6e − ⟶ 2Cr3+ Green + 7H2O In alkaline solution, orange colour of Cr2O7 2- changes to yellow colour due to formation of CrO4 2– and again yellow colour changes to orange colour on changing the solution to acidic medium. Cr2O7 2− + 2OH− ⟶ 2CrO4 2− Yellow + H2O 2CrO4 2− Yellow + 2H + ⟶ 2Cr2O7 2− Orange + H2O CrO4 2- and Cr2O7 2- exist in equilibrium at pH = 4 and are interconvertible by altering the pH of the solution. When heated with H2SO4 and metal chloride, K2Cr2O7 gives vapours of chromyl chloride (CrO2Cl2). Chromyl chloride (CrO2Cl2) when passed into aqueous NaOH solution, yellow colour solution of CrO4 2– is obtained. This on reaction with lead acetate gives yellow ppt. of PbCrO4. When H2O2 is added to an acidified solution of dichromate ion, a complicated reaction occurs. The products obtained depend on the pH and concentration of Cr. Cr2O7 2− + 2H + + 4H2O2 ⟶ 2CrO(O2 )2 + 5H2O A deep blue-violet coloured peroxo compound, CrO(O2)2, called chromic peroxide is formed. This decomposes rapidly in aqueous solution into Cr+3 and oxygen. 15. What happens when a solution of potassium chromate is treated with an excess of dilute nitric acid? (1) Cr3+ and Cr2O7 2- are formed (2) Cr2O7 2- and H2O are formed (3) CrO4 2– is reduced to +3 state of Cr (4) CrO4 2– is reduced to 0 state of Cr 16. Which of the following statement is wrong when a mixture of NaCl and K2Cr2O7 is gently warmed with conc. H2SO4? (1) A deep red vapour is evolved (2) The vapour when passed through NaOH solution gives a yellow solution of Na2CrO4 (3) Chlorine gas is formed (4) Chromyl chloride is formed 17. The CrO3 on reaction with HCl and NaOH(aq.) gives respectively: (1) CrO2Cl2, CrO4 2- (2) Cr(OH)2, CrO4 2– (3) Cl2, Cr2O7 2– (4) Cl2, Cr(OH)3 18. Number of mole of K2Cr2O7 reduced by one mole of Sn2+ ions in acidic medium is : (1) 1/3 (2) 3 (3) 1/6 (4) 6 19. The equivalent mass of barium in BaCrO4 used as an oxidizing agent in acidic medium is (atomic mass of Ba = 137.34 and Cr = 52) (1) 137.34 (2) 85.78 (3) 114.45 (4) 68.67 20. The equivalent mass of KIO3 in the reaction 2Cr(OH)3 + OH– + KIO3 ⟶ 2CrO4 2- + KI + 5H2O (1) Molar mass (2) M/3 (3) M/6 (4) M/2
3 21. When H2O2 is added to an acidified solution of K2Cr2O7, then: (1) solution turns green due to formation of Cr2O3 and reduction of Cr takes place (2) solution turns blue due to formation of CrO(O2)2 and no redox change (3) a deep blue-violet coloured compound CrO(O2)2 due to reduction of Cr (4) solution gives green ppt. CrO(O2)2 due to oxidation of Cr 22. The colour of Cu2Cr2O7 solution in water is: (1) green (2) blue (3) orange (4) black Integer Type Questions – Single Digit (0–9) 23. A mixture of CS2 and H2S when oxidized yields a mixture of CO2, SO2 and H2O(g), which exerts a pressure of 7.2 atm, when collected in 82.1 L vessel at 327°C. To oxidize SO2 in the mixture, 7 L of 2 N - iodine was required. Moles of CS2 in the mixture is 24. A mixture of Xe and F2 was heated. A sample of white solid thus formed reacted with hydrogen to give 56ml of Xe at 0°C and 1 atm and HF formed required 60ml of 0.25M – NaOH for complete neutralization. If the molecular formula of the solid formed is XeFx, then the value of x is 25. One litre of a sample of ozonized oxygen at 0°C and 1 atm on passing through a KI solution, liberated iodine which required 9ml of a thiosulphate solution. A volume of 12ml of a '5.675 volume' hydrogen peroxide solution liberated iodine from another iodide solution, which required 24ml of the same thiosulphate solution. The volume percent of ozone in the ozonized oxygen sample is approximately Matrix – Match Type Questions 26. Match the columns. Column I (A) 50ml of 0.5M-Na2CO3 solution using methyl orange indicator. (B) 50ml of 0.5M-Na2CO3 solution using phenolphthalein indicator. (C) 50ml of 0.5M-NaHCO3 solution using methyl orange indicator. (D) 50ml of 0.5M-NaOH solution using phenolphthalein indicator. Column II (Solution needed for complete reaction) (P) 50ml of 0.5M-H2SO4 solution (Q) 50ml of 0.5M-HCl solution (R) 25ml of 0.5M-H2SO4 solution (S) 50ml of 1.0M-HCl solution (1) A→P, S; B→Q, R; C→Q,R; D→Q,R (2) A→P, Q; B→Q, R; C→Q, P; D→Q, R (3) A→P, S; B→Q, S; C→Q, P; D→Q, R (4) A→P, R; B→Q, P; C→Q, S; D→Q, R
4 Answer Key 1 . ( 2 ) 2 . ( 1 ) 3 . ( 1 ) 4 . ( 3 ) 5 . ( 3 ) 6 . (2, 4 ) 7 . (1, 2, 3 ) 8 . (1, 2, 3 ) 9 . ( 1 ) 10 . (1, 2, 3 ) 11 . ( 1, 2 ) 12 . ( 4 ) 13 . ( 3 ) 14 . ( 1 ) 15 . ( 2 ) 16 . ( 3 ) 17 . ( 1 ) 18 . ( 1 ) 19 . ( 2 ) 20 . ( 3 ) 21 . ( 2 ) 22. (1) 23 . ( 2 ) 24 . ( 6 ) 25 . ( 5 ) 26 . ( 1 )