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Page # 18 STOICHIOMETRY - II Exercise - I (Only one option is correct) 1. The equivalent weight of MnSO4 is half its molecular weight when it is converted to : (A) Mn2O3 (B) MnO2 (C) MnO4 ñ (D) MnO4 2ñ 2. Given the equation S2O8 2ñ + 2eñ  2SO4 2ñ , Mn2+ + 4H2O  MnO4 ñ + 8H+ + 5eñ . How many moles of S2O8 2ñ ions are require to oxiDes 1 mole of Mn2+: (A) 0.4 (B) 0.5 (C) 2.5 (D) 1.0 3. A solution of 10 ml 0.1 M FeSO4 was titrated with KMnO4 solution in acidic medium. The amount of KMnO4 used will be: (A) 5 ml of 0.1 M (B) 10 ml of 0.1 M (C) 10 ml of 0.5 M (D) 10 ml of 0.02 M 4. NH2OH reacts with ferric sulphate as follows : 2NH2OH + 4 Fe3+  N2O + H2O + 4 Fe2+ 4H+. The eq. wt. of NH2OH in this reaction is : (A) (mol. wt.)/1 (B) (mol.wt.)/2 (C) (mol.wt.)/3 (D) (mol.wt.)/4 5. 20 ml of 0.1 M solution of metal ion reaCteD with 20 ml of 0.1 M SO2 solution. SO2 reacted according to the equation. SO2 + 2H2O  SO4 2ñ + 4H+_ + 2eñ . If the oxidation no. of metal ion was +3, the new oxidation number of the metal would be: (A) 0 (B) +1 (C) +2 (D) None of these 6. How many ml of 0.150 M Na2CrO4 will be required to oxidize 40 ml of 0.5 M Na2S2O3 . CrO4 2ñ + S2O3 2ñ Cr(OH)4 ñ + SO4 2ñ . (A) 225 ml (B) 355 ml (C) 455 ml (D) 555 ml 7. Number of moles of electrons take up when 1 mole of NO3 ñ ions is reduced to 1 mole of NH2OH is: (A) 2 (B) 4 (C) 5 (D) 6 8. The number of moles of thiosulphate (S2O3 2ñ) that will required to react completely with one mole I2 in alkaline medium (where it gets oxidised to SO4 2ñ) is : (A) 1/4 (B) 4 (C) 8 (D) 1/8 9. The number of moles of oxalate KHC2O4 . H2C2O4 .2H2O oxidised by one mole of permanganate ion is: (A) 3/4 (B) 1 (C) 5/4 (D) 6/4 10. How many equivalents are there per mol of H2S in its oxidation to SO2 ? (A) 2 (B) 4 (C) 6 (D) 8 11. 3 mol of a mixture of FeSO4 and Fe2(SO4) 3 required 100 mL of 2M KMnO4 solution is acidic medium . Hence mol fraction of FeSO4 in the mixture is: (A) 1/3 (B) 2/3 (C) 2/5 (D) 3/5 12. In a reaction 4 moles of electron are transferred to one mole of HNO3 . When acted as an oxidant. The possible reduction product is : (A) 1/2 mole of N2 (B) 1/2 mole of N2O (C) 1 mole of NO2 (D) 1 mole of NH3 13. One mole of N2H4 loses ten moles of electrons to from a new Compound y. Assuming that all the nitrogen appears in the new compound. What is the oxidation state of nitrogen in y. There is no change in the oxidation state of hydrogen: (A) ñ1 (B) ñ3 (C) + 3 (D) +5 14. 1 g equiv of a substance is the weight of that amount of a substance which is equivalent to : (A) 0.25 mol of O2 (B) 0.50 mol of O2 (C) 1 mol of O2 (D) 8 mol of O2 15. Which of the following changes requires reducing agent? (A) CrO4 2ñ  Cr2O7 2ñ (B) BrO3 ñ  BrOñ (C) H2AO3  HAsO4 2ñ (D) Al(OH)3 Al(OH)4 ñ 16. Which of the following is a disproportonation reaction? (A) CaCO3 + 2H+  Ca2+ + H2O + CO2 (B) 2CrO4 2ñ + 2H+  Cr2O7 2+ + H2O (C) Cr2O4 2ñ + 2OHñ  2CrO4 2ñ + H2O (D) Cu2O + 2H+  Cu + Cu2+ + H2O 17. If equal volumes of 1M KMnO4 and 1M K2Cr2O7 solutions are allowed to oxidise Fe2+ in acidic medium. The amount of iron oxidised will Be : (A) more by KMnO4 solution (B) more by K2Cr2O7 solution (C) equal in both the cases (D) cannot be determined
STOICHIOMETRY - II Page # 19 18. In the following reaction (unbalanced), equivalent wt. of As2S3 is related to molecular wt. M By: As2S3 + H+ NO3 ñ  NO + H2O + AsO4 3ñ + SO4 2ñ (A) M/2 (B) M/4 (C) M/28 (D) M/24 19. Mass of KHC2O4 (potassium acid oxalate) required to reduce 100 mL of 0.02 M KMnO4 in acidic medium (to Mn2+) is x g, and to neutralise 100 mL of 0.05 M Ca(OH)2 is y g then : (A) x = y (B) 2x = y (C) x = 2y (D) None is CorreCt 20. 100 mL of 1 M KMnO4 oxidised 100 mL of H2O2 in acidic medium (when MnO4 ñ is reduced to Mn2+) ; volume of same KMnO4 required to oxidise 100 mL of H2O2 in basic medium (when MnO4 ñ is reduced to MnO2) will be: (A) (100/3) mL (B) (500/3) mL (C) (300/5 ) mL (D) 100 mL 21. 1 mol of ferric oxalate is oxidised by x mol of MnO4 ñ and also 1 mol of ferrous oxalate is oxidised By y mol of MnO4 ñ in acidic medium. The ratio (x/ y) is: (A) 2 : 1 (B) 1 : 2 (C) 3 : 1 (D) 1 : 3 22. 0.7 gm of Na2CO3 .xH2O is dissolved in 100 ml, 20 ml of which required 19.8 ml of 0.1 N HCl. The value of x is: (A) 4 (B) 3 (C) 2 (D) 1 23. A metal is burnt in oxygen and all the products of combustion are weighed. It is found that the wt. of the metal seems to have increased by 24%. The equivalent wt. of the above metal. (A) 25 (B) 24 (C) 33.34 (D) 76 24. When one gm mole of KMnO4 reacts with HCl, the volume of chlorine liberated at NTP will be: (A) 11.2 litre (B) 22.4 litre (C) 44.8 litre (D) 56.0 litre 25. 10.78 g of H3PO4 in 550 mL solution is 0.40 N. Thus this acid: (A) has been neutralised to HPO4 2ñ (B) has been neutralised to PO4 3ñ (C) has been reduced to HPO3 2ñ (D) has been neutralised to H2PO4 ñ 26. When 0.75 gm of a substance was kjeldalised, it produced NH3 . Which neutralizes 30 ml of 0.25 N sulphuric acid. The percentage of nitrogen in the organic compound is : (A) 14 (B) 11 (C) 1 (D) None 27. 15 mol of KMnO4 are treated with excess H2C2O4 in H2SO4 medium. How many moles of CO2 will be formed and how many moles of H2C2O4 will be consumed? (A) 75, 37, 5. (B) 3, 15 (C) 3, 6 (D) 75, 150 28. An equimolar mixture of NaHC2O4 and H2C2O4 consumes 20 ml 0.3 M NaOH solution for complete neutralization. The same mixture requires V ml. 0.05 M KMnO4 solution in acidic medium for oxidation. The value of V is : (A) 160 ml (B) 32 ml (C) 24 ml (D) None of these Question No. 29 to 32 (4 questions) 30cc of a solution containing 9.15 gm of salt KxHY (C2O4) z. nH2O per litre required 27cc of 0.12 N NaOH for neutralization. The same quantity of solution was also found to require 36cc of 0.12 N KMnO4 solution for complete oxidation. 29. What is the value of X (A) 1 (B) 2 (C) 3 (D) 4 30. What is the value of Y (A) 4 (B) 3 (C) 2 (D) 1 31. What is the value of Z (A) 4 (B) 1 (C) 2 (D) 3 32. What is the value of n (A) 4 (B) 3 (C) 1 (D) 2
Page # 20 STOICHIOMETRY - II Question No. 33 to 35 (3 questions) A steel sample is to be analysed for Cr and Mn simultaneously. By suitable treatment Cr is oxidized as Cr2O7 2ñ and the Mn to MnO4 ñ . Cr  Cr2O7 2ñ Mn  MnO4 ñ A 10 gm sample of steel is used to produce 250.0 mL of a solution containing Cr2O7 2ñ and MnO4 ñ . A 10 mL portion of this solution is added to a BaCl2 solution and by proper adjustment of the acidity, the chromium is completely precipitated as BaCrO4 ; 0.0549 g is obtained. Cr O BaCrO H 2 7 2 4 ñ    A second 10 mL portion of this solution requires exactly 15.95 mL of 0.0750 M standard Fe2+ solution for its titration (in acid solution) 33. % of chromium in the steel sample (A) 1.496 (B) 2.82 (C) 1.96 (D) 5 34. Equivalent of Fe2+ required for reduction of MnO4 ñ is (A) 5.44 × 10ñ4 (B) 0.544 × 10ñ2 (C) 1.196 × 10ñ3 (D) 11.96 × 10ñ4 35. Amount of BaCl2 required for conversion of Cr2O7 2ñ to BaCrO4 in steel sample (A) 0.045 (B) 0.0549 (C) 1.125 (D) 2.82 Question No. 36 to 38 (3 questions) 25 ml from a stock solution containing NaHCO3 and Na2CO3 was diluted to 250 ml with CO2 free distilled water. 25 ml of the diluted solution when titrated with 0.12 M HCl required 8 ml., when phenolphthalein was used as an indicator. Na2CO3 + HCl HPh   NaHCO3 When 20 ml of diluted solution was titrated with same acid it required 18 ml when methlyorange was used as an indicator. Na2CO3 + 2HCl MeOH   2NaCl + H2O + CO2 NaHCO3 + HCl MeOH   NaCl + H2O + CO2 36. Concentration of NaHCO3 in gm/lit. (A) 0.312 (B) 2.62 (C) 3.12 (D) 26.208 37. Amount of NaOH that should be added to convert all bicarbonate into carbonate in 100 ml stock solution (A) 1.248 gm (B) 0.312 gm (C) 3.12 × 10ñ2 gm (D) 7.8 × 10ñ3 gm 38. Millimoles of NaHCO3 present in stock solution (A) 0.624 (B) 2.16 (C) 1.536 (D) 7.8 Question No. 39 to 41 (3 questions) 1.16 g CH3(CH2) n COOH was burnt in excess air and the resultant gases (CO2 and H2O) were passed through excess NaOH solution. The resulting solution was divided in two equal parts. One part requires 50 mL of 1 N HCl for neutralization using phenolphthalein as indicator. Another part required 80 mL of 1 N HCl for neutralization using methyl orange as indicator. 39. Produced mole of the CO2 (A) 0.1 (B) 0.01 (C) 0.06 (D) None of these 40. What is the value of n (A) 4 (B) 3 (C) 2 (D) 1 41. Amount of excess NaOH solution taken initially. (A) 3.2 gm (B) 6.4 gm (C) 1.2 gm (D) None of these