Transition Elements Exercise # 2

Exercise # 2 Part # I [Multiple Correct Choice Type Questions] 1. The colour of the transition metal ions is/are due to : (A) d-d transition of electrons in presence of ligands (B) charge transfer from ligand to metal ion. (C) change in the geometry (D) polarisation of anion by cation 2. Which of the following statement(s) is/are not correct ? (A) The blue colour of aqueous CuCl2 is due to [Cu(H2O)4]2+ (B) The yellow colour of aqueous CuCl2 is due to [CuCl4]2– (C) The green colour of aqueous CuCl2 is due to the presence of both [Cu(H2O)4]2+ and [CuCl4]2– (D) The blue colour of aqueous CuCl2 is due to [CuCl4]2– 3. Select correct statement (s). (A) MnO4– is intense pink colour due to d-d transition of electron. (B) Cu(I) is diamagnetic while Cu(II) is paramagnetic. (C) CrO3 is amphoteric oxide. (D) [Ti(H2O)6]3+ and [Sc(H2O)6]3+ both are coloured in aqueous solution. 4 In photography, quinol is used as developer according to following reaction. HO – – OH + 2AgBr + 2OH–  O= = O + 2Ag + 2H2O + 2Br– Which of the following describe(s) the role of quinol in this reaction ? (A) It acts as an acid. (B) It acts as a weak base. (C) It acts as an oxidising agent. (D) It acts as a reducing agent. 5. Which of the following statement (s) is/are correct ? (A) S2O82– oxidise Ag+ in presence of pyridine and give red colour compound. (B) MnO42– disproportionates to yield MnO4– and MnO2 in presence of H+ ions. (C) In Cr2O72– each Cr is linked to four oxygen atoms. (D) Ti3+ is purple while Ti4+ is colourless. 6. Following reaction(s) is/are involved in the iodometric estimation. (A) Cr2 O72– + H+ + –  2Cr3+ + 2 ; 2 + S2O32–  S4O62– + – (B) MnO4– + H+ + –  Mn2+ + 2 ; 2 + S2 O32–  S4 O62– + – (C) MnO4– + OH– + –  MnO2 + 2 ; 2 + S2O32–  S4O62– + – (D) Cr2 O72– + OH– + –  2 Cr3+ + 2 ; 2 + S2 O32–  S4O62– + – 7. Correct statements about transition metals are that they : (A) form complex (B) show variable oxidation states (C) show magnetic properties (D) do not form coloured compounds 8. Transition elements have greater tendency to form complexes because they have : (A) vacant d–orbitals (B) small size (C) higher nuclear charge (D) variable oxidation states 9. Which of the following statements are correct when a mixture of NaCl and K2Cr2O7 is gently warmed with conc. H2SO4 ? (A) Deep red vapours are liberated (B) Deep red vapours dissolve in NaOH (aq.)forming a yellow solution. (C) Greenish yellow gas is liberated (D) Deep red vapours dissolve in water forming yellow solution TRANSITION ELEMENTS 10. Which of the following chemical reaction(s) is/are involved in developing of photographic plate ? (A) C6H4(OH)2 + 2AgBr  2Ag + C6H4O2 + 2HBr (B) AgBr + 2Na2S2O3  Na3 [Ag(S2O3)2] + NaBr (C) 2AgNO3 + Na2S2O3  Ag2S2O3 + 2NaNO3 (D) AgNO3 + KCN  AgCN + KNO3 11. Pyrolusite is MnO2 used to prepare KMnO4. Steps are : I II  MnO42–  MnO4– MnO2  Steps I and II are respectively : (A) fuse with KOH / air, electrolytic oxidation (B) fuse with KOH / KNO3 , electrolytic oxidation (C) fuse with concentrated HNO3 / air, electrolytic reduction (D) dissolve in H2O, oxidation 12. Which are correct statements ? (A) In less acidic solution K2Cr2O7 and H2O2 gives violet coloured diamagnetic [CrO(O2)(OH)]– ion. (B) In alkaline H2O2, K2CrO8 (with tetraperoxo species [Cr(O2)4]3–) is formed with K2Cr2O7. (C) In ammonical solution of H2O2, (NH3)3CrO4 is formed with K2Cr2O7. (D) CrO42– changes to Cr2O72– by oxidation. 13. Which of the following reaction(s) is/are incorrect for silver nitrate ? (A) 6 AgNO3 + 3I2 (excess) + 3 H2O  AgIO3 + 5 AgI + 6HNO3 (B) AgNO3 (excess) + 2 KCN  K[Ag(CN)2] + KNO3 (C) 2AgNO3 + 4Na2S2O3(excess)  2Na3[Ag(S2O3)2] + 2NaNO3 (D) PH3 + 6AgNO3 + 3H2O  6Ag + 6HNO3 + H3PO3 14. Which of the following reaction(s) is/are used for the preparation of anhydrous FeCl3 ? (A) FeCl3 6H2O + 6SOCl2  FeCl3 + 12HCl + 6SO2 (B) Fe(OH)3  + 3HCl  FeCl3 + 3H2O (C) 2Fe + 4HCl (aq.) + Cl2  2FeCl3 + 2H2 (D) 2Fe + 3Cl2(dry)  2FeCl3 15. Which of the following is/are false ? (A) Na2Cr2O7 is used as a primary standard in volumetric analysis. (B) Potassium permanganate in excess on treatment with conc. H2SO4 forms manganese heptoxide (C) Phosphine, arsine and stibine all precipitates silver from silver nitrate (D) From kipp's apparatus waste ferric sulphate and ferrous sulphate mixture is obtained when air or oxygen is passed for longer time. 16. When CO2 is passed into aqueous : (A) Na2CrO4 solution, its yellow colour changes to orange. (B) K2MnO4 solution, it disproportionates to KMnO4 and MnO2 (C) Na2Cr2O7 solution, its orange colour changes to green (D) KMnO4 solution, its pink colour changes to green. 17. Which of the following statement(s) is/are correct ? (A) Transition metals and many of their compounds show paramagnetic behaviour. (B) The enthalpies of atomisation of the transition metals are high. (C) The transition metals generally form coloured compounds. (D) Transition metals and their many compounds act as good catalyst. 18. Potassium manganate (K2MnO4) is formed when : (A) potassium permanganate reacts with formaldehyde in acidic medium. (B) manganese dioxide is fused with potassium hydroxide in air. (C) manganese hydroxide reacts with K2O2 in alkaline medium. (D) potassium permanganate is heated at 750K. 19. Select the incorrect statement(s) : (A) In K2MnO4 and CrO2Cl2, the central transition metals/ions have same oxidation state. (B) Both sodium and potassium dichromate can be used as primary standard in volumetric estimations. (C) Potassium dichromate on strong heating evolves oxygen gas and forms green powder. (D) Potassium permanganate on heating with solid KOH evolves oxygen gas and forms a black powder. 20. Select the correct statement(s) with respect to oxides and oxoanions of transition metals. (A) Among oxides of chromium, CrO is basic, Cr 2O3 is amphoteric and CrO3 is acidic. (B) No higher oxides of iron above Fe 2O3 are found. (C)Ti,V, Cr and Mn form oxides MO and their correct increasing order of acidic character is MnO 25Mn and 28Ni < 29Cu > 30Zn (C) Ni(II) compounds are more stable than Pt(II) where as Pt(IV) compounds are more stable than nickel (IV). (D) The elements which gives the greatest number of oxidation states does not occur in or near the middle of the series. 69. Which of the following ions give(s) colourled aqueous solution? (A) Ni2+ (B) Fe2+ (C) Cu2+ (D) Cu+ 70. Which of the following statement is/are correct ? (A) Transition metals and their many compounds act as good catalyst. (B) The enthalpies of atomistation of the transition metals are high. (C) The transition metals generally form interstitial compounds with small atoms like C, B, H etc. (D) All transition metal compounds are not paramagnetic. 71. Select correct statement (s). (A) PH3 reduces AgNO3 to metallic Ag. (B) Organic tissues turn AgNO3 black by reducing it to Ag. (C) AgCN is soluble in KCN. (D) Zr and Ta have almost similar size due to lanthanide contraction. TRANSITION ELEMENTS Part # II [Assertion & Reason Type Questions] Each question has 5 choices (A), (B), (C), (D) and (E) out of which only one is correct. (A) Statement-1 is true, Statement-2 is true and Statement-2 is correct explanation for Statement-1 (B) Statement-1 is true, Statement-2 is true and Statement-2 is not correct explanation for Statement-1 (C) Statement-1 is true, Statement-2 is false (D) Statement-1 is false, Statement-2 is true (E) Both Statements are false 1. Statement-1 : Mn atom loses ns electrons first during ionisation as compared to (n – 1) d-electrons. Statement-2 : The effective nuclear charge experienced by (n – 1) d electrons is greater than that by ns electron. 2. Statement-1 : CuSO4.5H2O on heating to 250°C loses all the five H2O molecules and becomes anhydrous. Statement-2 : All the five H2O molecules are co-ordinated to the central Cu2+ ion. 3. Statement-1 : Silver chloride dissolves in excess ammonia. Statement-2 : AgCl forms a soluble complex, [Ag(NH3 )2] Cl with ammonia. 4. Statement-1 : The order of atomic radii of Cu, Ag and Au is Cu < Ag  Au. Statement-2 : The atomic radii of 4d series elements are larger than those of 3d series elements but generally the radii of 4d and 5d series elements are almost identical. 5. Statement-1 :4d & 5d series elements have nearly same atomic radius. Statement-2 :Lanthanoide contraction. 6. Statement-1 : Statement-2 : Statement-1 : Statement-2 : 7. Tungsten has very high melting point Tungsten is a covalent compound CrO3 is an acid anhydride. CrO3 is obtained as bright orange crystals by the reaction of K2Cr2O7 with cold concentrated H2SO4. 8. Statement-1 : Solid potassium dichromate gives greenish yellow vapours with concentrated H2SO4 and solid ammonium chloride. Statement-2 : The reaction of ammonium chloride with solid K2Cr2O7 and concentrated H2SO4 produces chromyl chloride. 9. Statement-1 : Permanganate titrations is not carried out in presence of hydrochloric acid. Statement-2 : Hydrochloric acid is oxidised to chlorine. 10. Statement-1 : Copper metal is turned green when exposed to atmospheric CO2 and moisture. Statement-2 : Copper gets covered with a green layer of basic copper carbonate. 11. Statement-1 : Ammoniacal silver nitrate converts glucose to gluconic acid and metallic silver is precipitated. Statement-2 : Glucose acts as a weak reducing agent. 12. Statement-1 : 4d & 5d series elements have nearly same atomic radius. Statement-2 : Lanthanoide contraction. 13. Statement-1 : The free gaseous chromium atom has six unpaired electrons. Statement-2 : Half filled orbital has greater stability than fully filled. 14. Statement-1 : K2CrO4 has yellow colour due to charge transfer. Statement-2 : CrO42– ion is tetrahedral in shape. 15. Statement-1 : The green manganate is paramagnetic but the purple permanganate is diamagnetic in nature. Statement-2 : MnO42– contains one unpaired electron while in MnO4– all electrons are paired. 16. Statement-1 : The highest manganese fluoride is MnF4 and the highest oxide is Mn2O7 . Statement-2 : In Mn2O7, each Mn is tetrahedrally surrounded by Os including Mn–O–Mn bridge. 17. Statement-1 : The lowest oxide of a transition metal (say, chromium, atomic number 24) is basic where as the highest oxide is usually acidic. Statement-2 : Cr2O3 is amphoteric in nature. 18. Statement-1 : In acid solution permanganate is reduced to Mn2+ by an excess of reducing agent. Statement-2 : MnO4– redused in Mn2+ in acidic medium and the product in the presence of an excess of permanganate is MnO2 . 19. Statement-1 : The number of unpaired electrons in the following gaseous ions ; Mn3+, Cr3+, V3+ and Ti3+ are 4, 3, 2 and 1 respectively. 3+ Statement-2 : Cr is most stable in aqueous solution amongst these ions . 20. Statement-1 : The value of enthalpy of atomisation is maximum at about the middle of each series. Statement-2 : There is one unpaired electron per d-orbital and this results in stronger interatomic interaction. 21. Statement-1 : The spin only magnetic moment of Sc3+ is 1.73 B.M. Statement-2 : The spin only magnetic moment of an ion is equal to n(n  2) ; where n is the number of unpaired electrons in the ion. 22. Statement-1 : Hydrochloric acid is not used to acidify a KMnO4 solution in volumetric analysis of Fe2+ and C2O42– because. Statement-2 : Part of the oxygen produced from KMnO4 and HCl is used up in oxidising HCl to Cl2 . 23. Statement-1 : Potassium dichromates gives deep red vapours with concentrated H2SO4 and sodium chloride. Statement-2 : The reaction of sodium chloride with solid K2Cr2O7 and concentrated H2SO4 produces chromyl chloride. 24. Statement-1 : Solution of Na2CrO4 in water is intensely coloured. Statement-2 : Oxidation state of Cr in Na2CrO4 is (+VI). 25. Statement-1 : Silver nitrate is reduced to silver by the hydrides of 15th group elements (except NH3) because Statement-2 : They act as strong reducing agents. 26. Statement-1 : Ag2 S + 4 KCN 2K [Ag(CN)2] + K2S Statement-2 : The reaction is carried out in presence of air or O2 so that K2S is oxidised to K2SO4 thereby shifting the equilibrium in forward direction. 27. Statement-1 : Reaction of thionyl chloride with hydrated ferric chloride yields anhydrous ferric chloride. Statement-2 : Water of crystallisation present with ferric chloride reacts with thionyl chloride to liberate HCl and SO2 gases. 28. Statement-1 : Hydroquinone is used as a developer for developing black and white photographic film. Statement-2 : Hydroquinone reduces silver bromide to black silver particles and an inverted image of the object is produced on a celluloid film. TRANSITION ELEMENTS EXERCISE - 2 : PART # I 1. 10. 19. 29. 42. 55. 67. A, B, D A, B B, D C 30. D 43. A 56. A, C, D 2. 11. 20. C A D 68. D 3. A, B A, B 31. A 44. A 57. C A, B, C B 12. 21. 32. 45. 58. 69. 4. A, D A, B, C 13. A, B, D 22. A 33. D B 46. B A 59. A A, B, C 70. 5. A, B, C, D 6. A, B 7. A, B 14. A, D 15. A 16. A, B 23. A, B, D 24. A, B 34. D 35. B 36. D 37. C 47. C 48. C 49. A 50. A 60. A 61. D 62. A 63. C A, B, C, D 71. A, B, C A, B, C A, B 25. B 38. B 51. D 64. D 8. 17. 26. 39. 52. 65. A, B, C 9. A, B, D A, B, C, D 18. B, C, D A 27. A 28. B C 40. C 41. D D 53. B 54. A C 66. A, C 10. A 23. A 11. A 24. B PART # II 1. A 14. B 27. A 2. C 15. A 28. A 3. A 16. B 4. B 17. B 5. A 18. B 6. C 19. B 7. B 20. A 8. D 21. D 9. A 22. A 12. A 25. A 13. C 26. A