(ii) Zr and Hf have almost identical radii. Answer: (i) With the same d-orbital configuration (d4), Cr2+ ion is a reducing agent while Mn3+ ion is an oxidising agent. (i) Transition metals and their compounds generally exhibit a paramagnetic behaviour. 58)? (iii) Among the 3d series of transition elements, the largest number of oxidation states are exhibited by manganese. Question 62: When the manganese atom is oxidized, it becomes more electronegative. Answer: (ii) The metallic radii of the third (5d) series of transition elements are virtually the same as those of the corresponding members of the second series. View Answer. Explain the following observations: (i) The enthalpies of atomization of transition elements are quite high. Answer: 3) The principal O.S are + 3 and + 4 , ( + 3 oxidation state … (i) Why is E (Cu 2 + / Cu) 0 value exceptionally positive? Manganese. Answer: (iii) Transition metals and their compounds act as catalyst. None of the oxygen-containing compounds are peroxides or superoxides. (b) (i) Refer Ans. to Q.29 (ii). (ii) Among the divalent cations in the first series of transition elements, manganese exhibits the maximum paramagnetism. 4f and 5d levels being close in energies. Why Zn generally do not show oxidation state greater than 2 ? Question 45: nos. The most important isotope is 239 Pu because it is fissionable and has a half-life of 24,100 years, which makes it easy for chemists to study. Question 29: Similarity: (ii) The actinoids exhibit a large number of oxidation states than the corresponding members in the lanthanoid series. The energies are decided on the basis of (n+l) rule. to Q.30 (iii). Write one similarity and one difference between the chemistry of lanthanoids and that of actinoids. (ii)Oxidation States. Dissimilarity: (a) Complete the following equations: Iron has two common oxidation states (+2 and +3) in, for example, Fe 2+ and Fe 3+. It is due to similar energy of (n – 1 )d and ns orbitals, electrons from both can be lost. I know that this may be an overgeneralization, since depending on the type (i.e metals, non metals, etc) it will be different. Ytterbium (Yb) also shows +2 oxidation state. to Q.41 (ii). (i) Many of the transition elements and their compounds can act as good catalysis. (ii) There occurs much more frequent metal-metal bonding in compounds of heavy transition elements (3rd series). (iii) Lanthanoids form primarily +3 ions, while the actinoids usually have higher oxidation states in their compounds, +4 or even +6 being typical. Answer: Answer: Consequences: However, they are difficult to separate from one another. (ii) Manganese exhibits the highest oxidation state of+7 among the 3d series of transition elements It is because electrons from (n – 1 )d and ns take part in bond formation. to Q.29 (i). How would you account for the following: (a) (i) Refer Ans. Examples of variable oxidation states in the transition metals. - or - email: password: Log in Forgot password? How does the acidified permanganate solution react with the following: 2Cu+ —–> Cu2+ + Cu (i) Transition metals show variable oxidation, states. Describe the preparation of KMn04 from pyrolusite ore (MnO4). Addition of 3% misch metal to magnesium increases its strength and used in making jet engine parts. Question 49: Question 22: (a) How would you account for the following: (ii) Actinoids exhibit greater range of oxidation states than lanthanoids. Why? All Actinides form oxides with different oxidation states. Answer: (i) Why do actinoids show wide range of oxidation states? (ii) It is because energy required to remove electron is more due to greater effective nuclear charge which is due to lanthanoid contraction. Answer: Obviously, reaction (4.4.17) right is the reverse of reaction (4.4.11).From laboratory investigations and studies of plant data, it has been noticed that reaction (4.4.17) does not reach the equilibrium. Give reasons : Answer: Lanthanide oxidation states All of the lanthanide elements are commonly known to have the +3 oxidation state and it was thought that only samarium, europium, and ytterbium had the +2 oxidation readily accessible in solution. (iii) Refer Ans. (iii) Complete the following equation: Answer: (iii) Refer Ans. (iii) The wide range of oxidation states of actinoids is attributed to the fact that the 5f, 6d and 7senergy levels are comparable energies. 3rd series). (ii)Oxidation States. (iii) The EMn2+/Mn, value for manganese is much more than expected from the trend for other elements in the series. Question 16: By that those ions become strong reducing or oxidizing agents respectively. (ii) Refer Ans. to Q.43 (b) (ii). (ii) Transition metals and their compounds show catalytic properties. Manganese has a very wide range of oxidation states in its compounds. Answer: Answer: The reason for greater range of oxidation states in actinoids is attributed to. to Q.47 (i) (a) Complete and balance the following chemical equations: Account for the following: The most common oxides are of the form M 2 O 3, where M would be one of the elements in the Actinide series. Question 53: (a) (i) Refer Ans. (i) La3+ (Z = 57) and La3+(Z = 71) do not show any colour in solutions: Question 66: (a) Refer Ans. 2MnO4 + 4KOH + O2 ———> (ii) Refer Ans. Therefore all these three sub shells can participate. There is repulsion between paired electrons. What happens when an acid solution of green coloured compound (B) is allowed to stand for some time. It contains 45% lanthanoid metals and iron (—5%) and traces of S, C, Ca and Al. (ii) It is because 5f, 6d and Is have comparable energy. 12 (a) (i). Actinides exhibits larger oxidation states than lanthanide because of very small energy gap between 5f, 6d and 7s subshells . 2 MnO4 + 6H+ + 5NO2 – ———-> This is due to the very small energy gap between 5f, 6d and 7s sub shells. Answer: Actinides form basic oxides and hydroxides. (i) Mn+2 is more stable than Mn+3 due to half filled d-orbitals (3d5), whereas Cr+3 is more stable than Cr+2 due to half filled orbitals. (iii) It is because oxygen and fluorine are strong oxidising agents, highly electronegative, small size and can provide energy for formation of transition metal ion in higher oxidation state. (ii) Cu(I) is not stable in an aqueous solution. In 3d series (Sc to Zn), which element shows the maximum number of oxidation states and why? Actinoids exhibits greater range of oxdn states than lanthenoids. This is because of large energy gap between 4f 5d and 6s subshell. (ii) 5f orbitals have poor shielding effect than 4f orbitals, therefore, effective nuclear charge is more in actinoids than lanthanoids. Find 1 Answer & Solution for the question Why do actinoids show a wide range of oxidation states ? (a) (i) Refer Ans. Misch metal is used in Mg-based alloy to produce bullets, shell and lighter flint. In d-block, oxidation states differ by one, whereas in p-block, it differs by two. (a) Which metal in the first transition series (3d series) exhibits +1 oxidation state most frequently and why? : La = 57, Lu = 71) Sc3+, V3+, Ti4+, Mn2+ Identify A, B, C and write the reactions involved. Question 15: The (n+l) values of the tree orbitals are as under: 5 f = 5 + 3 = 8. Unusual oxidation state; Common only for the heaviest elements; No 2+ & Md 2+ are more stable than Eu 2+; Actinide An 2+ ions have similar properties to Lanthanide Ln 2+ and to Ba 2+ ions; rationalization of stabilities: Open University Course Book p. 54-56 +3. Answer: (i) It is because 5f, 6d and 7s have comparable energy. The actinides (An) may be prepared by reduction of AnF3 or AnF4 with vapors of Li, Mg, Ca, or Ba at 1100-1400 C. (a) Complete the following chemical reaction equations: (i) It is because after losing 2 electrons and 4 electrons, they acquire stable configuration, i.e. 8. The known oxidation states of actinoids are listed in Table 8.11. In 3d series, ‘Mn’ shows maximum number of oxidation states because it has maximum number of electrons in s as well as in d orbitals which can take part in bond formation. Explain the following observations: (ii) Oxalic acid (C2H204) Answer: (ii) It is due to large number of unpaired electrons in d-orbitals in middle of the series. (b) (i) Refer Ans. Many actinide metals have properties of both d block and f block elements. (i) Copper (I) ion is not known in aqueous solution. The radioactive nature of actinoids. to Q.35 (i). (i) Mn04– + C2072- + H+ ——-> (ii) Refer Ans. (iii) The members in the actinoid series exhibit a larger number of oxidation states than the corresponding members in the lanthanoid series. Actinoids shows wide range of oxidation states due to the fact t hat the 5f,6d and 7s energy levels are of comparable energies.Therefore all these three subshells can participate. (ii) It is due to 5f electrons which are more effectively shielded than 4f electrons therefore, outer electrons are less firmly held and available for bonding in actinoids and they show a wide range of oxidation states. Delhi 2016) Answer: (i) Because in transitional elements ns and (n – 1 )d electrons have approximate equal energies. (i) The transition metal ions are usually coloured in aqueous solutions. Conversely, early actinides such as uranium, neptunium, and plutonium can adopt a number of oxidation states from+3 to +7 while typically avoiding the +2 state. (ii) E°CU2+/CU *ias +ve value due to high ionisation enthalpies and sublimation energies and lower hydration energy. Question 41: (v) Mn04 + 8H+ + 5e- ———> Mn2+ + 4H20. Examples of variable oxidation states in the transition metals. Changes of oxidation state therefore change the colour of the light absorbed, and so the colour of the light you see. Answer: (ii) Why is E (Mn 2 + / Mn) 0 value highly negative as compared to other elements? The oxidation state of a free element (uncombined element) is zero. (a) (i) Transition elements form interstitial compounds. (ii) It is because neither Zn nor Zn2+ ions have incompletely filled d-orbitals. Answer: (c) Sc3+ is colourless in aqueous solution, whereas Ti3+ is coloured. to Q.9 (ii). So, which do you mean? (a) (i) Atomic and covalent radii: The atomic radii decrease’ from Sc to Cr because number of unpaired electrons increases, therefore, effective nuclear charge increases. to Q.55 (i). Read the numbers at the top of the columns. Answer: (ii) There is a close similarity in physical and chemical properties of the 4d and 5d series of the transition elements, much more than expected on the basis of usual family relationship. Answer: (i) Refer Ans. (b) What is misch metal? Write on the similarity between the chemistry of lanthanoids and actinoids. (ii) Refer Ans. (i) Highest fluoride of Mn is MnF4 whereas the highest oxide is Mn2O2 (a) Copper exhibits +1 oxidation state frequently due to stable electronic configuration. to Q.5 (ii). Answer: (iii)Transition metals show variable oxidation states. Others are colourless due to the absence of unpaired electrons and cannot undergo d-d transitions. NCERT DC Pandey Sunil Batra HC Verma Pradeep Errorless. (iv) The value for copper is positive (+ 0.34 V). to Q.40 (iii). Question 44: The most common and stable oxidation state of Lanthanides is +3. (i) It is due to presence of vacant d-orbitals of suitable energy, smaller size of cations and higher charge. (iii) Refer Ans. Question 8: (b) (i) Refer Ans. (iii) The metallic radii of the third (5d) series of transition metals are nearly the same as those of the corresponding members of the second series. (i) Cu (I) ion is not stable in an aqueous solution. (iii) Refer Ans. Question 55: Answer: (i) Transition elements generally form coloured compounds. (i) With the same d-orbital configuration (d4), Cr2+ is a reducing agent while Mn3+ is an oxidising agent. Answer: Answer: Question 58: to Q.l. Why? Find 1 Answer & Solution for the question Why do actinoids show a wide range of oxidation states ? (i) It is due to presence of five unpaired electrons. Actinides show a variety of oxidation states from +3 to +6. You may need to download version 2.0 now from the Chrome Web Store. (iii) It is due to poor shield effect ofd, and f-orbitals, more unpaired electrons can take part in metal-metal bonds. (ii) Mn has electronic configuration (Ar) 4s2 3d5 and all the electrons in ‘s’ as well as ‘d’ orbitals can take part in bond formation, therefore, it shows + 7 highest oxidation state. Actinoids also show stable +3 oxidation state but show a number of oxidation states i.e. View Answer. (iii) Refer Ans. For example, uranium, neptunium and plutonium form salts of the Na 2 UO 4 (uranate) and (NH 4) 2 U 2 O 7 (diuranate) types. Examples of variable oxidation states in the transition metals. The wide range of oxidation states of actinoids is attributed to the fact that the 5f, 6d and 7s energy levels are of comparable energies. (a) How do you prepare: to Q.51 (ii) Why do actinoids show a wide range of oxidation states? Question 6: It has surface oxidation when exposed to air. (b) Complete the following equation: (ii) Refer Ans. (iii) Most of the transition metal ions exhibit characteristic colours in aqueous solutions All the lanthanide elements exhibit the oxidation state +3. 5 (ii). Answer: For example: (ii) There occurs much more frequent metal-metal bonding in compounds of heavy transition metals (i.e. (ii) Refer Ans. 5f, 6d and 7s levels having comparable energies. Answer: (i) It is because 5f, 6d and 7s have comparable energy. to Q.5 (ii). 1045 Views. (i) Cr2072- + I- + H+ ——–> Question 25: (a) (i) Refer Ans. (b) (i) 2KMn04———> K2Mn04+ MnO2+ O2 Answer: Question 27: Biology. Question 26: Assign reasons for the following :
(i) Copper (I) ion is not known in aqueous solution. For example, in a sulfite ion (SO 3 2- ), the total charge of the ion is 2-, and each oxygen is assumed to be in its usual oxidation state of -2. (ii) It is due to similar atomic size, they can replace one another in metallic bond. (b) (i) Calculate the spin magnetic moment of M2+(aq) ion. (c) Sc3+ is colourless as it does not have unpaired electron and cannot undergo d-d transition, whereas Ti3+ is coloured due to presence of unpaired electrons and undergoes d-d transition by absorbing light from visible region and radiate complementary colour. Mn207. (ii) Refer Ans. what are the most common oxidation states of iron. (iii) Lanthanum and Lutetium do not show colouration in solutions. (ii) Cr2O7-(aq) + Fe2+ (aq) + H+(aq) ——-> (b) V3+ and Mn2+ are coloured, due to the presence of unpaired electrons, they can undergo d-d transitions. Why Zn generally do not show oxidation state greater than 2 ? Stability of oxidation states. For example: to Q.23 (b). (a) Calculate the number of unpaired electrons in the following gaseous state ions: (i) It is due to presence of unpaired electrons in (i-orbitals therefore, they undergo d-d transitions by absorbing light from visible region and radiate complementary colour. Elements in other states hence try to lose or gain electrons to get +3 state. (iii) Actinoid elements show wide range of oxidation states. to Q.39 (ii). (iii) Actinoids show a wide range of oxidation states. (iv) Out of Mn3+ and Cr3+, which is more paramagnetic and why? Write one similarity between the chemistry of lanthanoids and actinoids… (c) Zn may not be regarded as transition metal because neither ‘Zn’ nor Zn2+ ions have incompletely filled d-orbital. (i) Metal-metal bonding is more extensive in the 4d and 5d series of transition elements than the 3d series. (i) The atomic radii of the metals of the third (5d) series of transition elements are virtually the same as those of the corresponding members of the second (4d) series. 3MnO4– + 4H+ ———> to Q.41 (ii). Actinides show variable oxidation states because of the smaller energy gap between 5f, 6 d and 7s orbitals. (iv) The silver atom has completely filled d-orbitals (4d 10 ) in its ground state, yet it is regarded as a transition element. Unusual oxidation state; Common only for the heaviest elements; No 2+ & Md 2+ are more stable than Eu 2+; Actinide An 2+ ions have similar properties to Lanthanide Ln 2+ and to Ba 2+ ions; rationalization of stabilities: Open University Course Book p. 54-56 +3. to Q. (At. (ii) Cr2O7-(aq) + H2S(g) + H+(ag) ——–> (i) With reference to structural variability and chemical reactivity, write the Differen ces between lanthanoids and actinoids. (iv) It is because of high ionisation enthalpy of Cu which is not compensated by hydration energy. Why dp transition elements show variable oxidation states? • (i) It is because of presence of unpaired electrons in d-orbitals of transition metal. to Q.47 (ii). (ii) Why is actinoid contraction greater than lanthanoid contraction? (b) Explain the following observations about the transition/inner transition elements: – The word valence is used inconsistently to mean either one or the other. If you are on a personal connection, like at home, you can run an anti-virus scan on your device to make sure it is not infected with malware. The E 0 ( M 2+ / M ) value of a metal depends on the energy changes involved in the formation of the M 2+ ion: (a) (i) EU2+ is strong reducing agent Secondly, in transition elements, incoming electron goes to inner shell (d-orbitals), whereas in main group elements, the incoming electron goes to outermost shell. Lanthanoids show mostly +3 oxidation state. forming unstable intermediates which readily change into products. Answer: to Q.16 (a) (ii). Mon to Sat - 10 AM to 7 PM (iii) Transition metals in general act as good catalysts. (ii) It is because Mn2+ is more stable than Mn3+ due to stable half filled 3d° configuration: In soils, the main source of electrons is carbon atoms of organic matter because carbon has a wide range of oxidation states. (ii) Cr2072 – + 14H+ + 6Fe2+ ———> 2Cr3+ + 7H20 + 6Fe3+. (i) The tendency to show number of oxidation states increases from Sc to Mn and then decreases because number of unpaired electrons increases till Mn, then decreases. The I.E. Answer: (a) (i) Cr2072- + 20H- ——–> 2CrO4– + H2O (iii) It is because 5f, 6d and 7s have comparable energy. Cloudflare Ray ID: 600a3b03883b16ee C. 5f, 6d and 7s levels having comparable energies. (iii) There is a greater range of oxidation states among the actinoids than among the lanthanoids. (i) It is due to lanthanoid contraction which is due to poor shielding effect of f-electrons. (ii) Mn(III) undergoes disproportionation reaction easily. (iii) Refer Ans. (iii) Cu+ ion is not known in aqueous solutions. (b) 3MnO4– + 4H+ ——–> MnO2 + 2MnO4– + 2H2O. (i) Transition metals generally form coloured compounds. (iii) The metal-metal bonding is more frequently found with the second and third series of transition elements. There are 15 known isotopes. (a) Lanthanoids, mostly show +3 oxidation state but some of them show +2 and +4 oxidation states also due to the stability of electronic configuration (4f°, 4f7 and 4f14), e.g. (i) There is in general an increase in density of element from titanium ‘ (Z = 22) to copper (Z = 29). Post author: Post published: December 2, 2020 Post category: Uncategorized Post comments: 0 Comments 0 Comments (b) Write two characteristics of the transition elements. Answer: Why? Refer Ans. The actinoids show in general +3 oxidation state. Actually, i believe its not JUST actinoids, but basically all elements that are period 5 and lower. to Q.59 (ii). (ii) Transition metals form coloured compounds (ii) Chromium is typical hard metal while mercury in liquid, explain. (b) Zinc does not have unpaired electrons and larger in size, therefore, it has weak metallic bonds. (ii) It is due to lanthanoid contraction which is due to poor shielding effect off-electrons, due to which effective nuclear charge increases, therefore, Zr and Hf have almost identical radii. Why? (ii) It is due to maximum number of unpaired electrons(s). (iii) Cobalt (II) is stable in aqueous solution but in the presence of complexing agents, it is easily oxidised. (i) Copper (I) ion is not stable in an aqueous solution. Answer: All of them are soft, have a silvery color (but tarnish in air), and have relatively high density and plasticity. (i) Mn04- (aq) + S2O32-(aq) + H20(l) ——-> (ii) Unlike Cr3+, Mn2+, Fe3+ and the subsequent other M2+ ions of the 3d series of elements, the 4d and the 5d series metals generally do not form stable cationic species. (i) number of oxidation states exhibited (ii) formation of oxometal ions. to Q.41 (ii). Question 38: (iii) Out of Cr3+ and Mn3+, which is a stronger oxidizing agent and why? to Q.67 (ii). (ii) Cu+ ion is not stable in aqueous solutions. 6 d = 6 + 2 = 8. This generally favours higher oxidation states and disfavours low oxidation states in actinides. (iii) Complete the following equation: (a) (i) Refer Ans. Zn+2 salts are white because it does not have unpaired electron, whereas Cu+2 salts are coloured because it has unpaired electron and undergoes d-d transition by absorbing light from visible region and radiate blue colour. (i) Mn(II) ion shows maximum paramagnetic character amongst the bivalent ions of first transition series. (iii) It is due to lanthanoid contraction, effective nuclear charge does not decrease, therefore, atomic size does not increase appreciably in the series of transition metals. (b) What is lanthanoid contraction? 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As +4, +6 and +7 oxidation states are +3 and +4 oxidation state than Co2+ to. Closely in their properties +2 complexes in solution between 5f, 6d and 7s orbitals much number. Stable configuration, i.e reference to structural variability and chemical reactivity, write the reactions involved the observations...: its magnesium based alloy is used to produce bullets, shells, flints the enthalpy of Cu is. E° value for the corresponding members in the solid state and third of... Than 2 in, for example: examples of variable oxidation states elements of...
(i) Copper (I) ion is not known in aqueous solution. For example, in a sulfite ion (SO 3 2- ), the total charge of the ion is 2-, and each oxygen is assumed to be in its usual oxidation state of -2. (ii) It is due to similar atomic size, they can replace one another in metallic bond. (b) (i) Calculate the spin magnetic moment of M2+(aq) ion. (c) Sc3+ is colourless as it does not have unpaired electron and cannot undergo d-d transition, whereas Ti3+ is coloured due to presence of unpaired electrons and undergoes d-d transition by absorbing light from visible region and radiate complementary colour. Mn207. (ii) Refer Ans. what are the most common oxidation states of iron. (iii) Lanthanum and Lutetium do not show colouration in solutions. (ii) Cr2O7-(aq) + Fe2+ (aq) + H+(aq) ——-> (b) V3+ and Mn2+ are coloured, due to the presence of unpaired electrons, they can undergo d-d transitions. Why Zn generally do not show oxidation state greater than 2 ? Stability of oxidation states. For example: to Q.23 (b). (a) Calculate the number of unpaired electrons in the following gaseous state ions: (i) It is due to presence of unpaired electrons in (i-orbitals therefore, they undergo d-d transitions by absorbing light from visible region and radiate complementary colour. Elements in other states hence try to lose or gain electrons to get +3 state. (iii) Actinoid elements show wide range of oxidation states. to Q.39 (ii). (iii) Actinoids show a wide range of oxidation states. (iv) Out of Mn3+ and Cr3+, which is more paramagnetic and why? Write one similarity between the chemistry of lanthanoids and actinoids… (c) Zn may not be regarded as transition metal because neither ‘Zn’ nor Zn2+ ions have incompletely filled d-orbital. (i) Metal-metal bonding is more extensive in the 4d and 5d series of transition elements than the 3d series. (i) The atomic radii of the metals of the third (5d) series of transition elements are virtually the same as those of the corresponding members of the second (4d) series. 3MnO4– + 4H+ ———> to Q.41 (ii). Actinides show variable oxidation states because of the smaller energy gap between 5f, 6 d and 7s orbitals. (iv) The silver atom has completely filled d-orbitals (4d 10 ) in its ground state, yet it is regarded as a transition element. Unusual oxidation state; Common only for the heaviest elements; No 2+ & Md 2+ are more stable than Eu 2+; Actinide An 2+ ions have similar properties to Lanthanide Ln 2+ and to Ba 2+ ions; rationalization of stabilities: Open University Course Book p. 54-56 +3. to Q. (At. (ii) Cr2O7-(aq) + H2S(g) + H+(ag) ——–> (i) With reference to structural variability and chemical reactivity, write the Differen ces between lanthanoids and actinoids. (iv) It is because of high ionisation enthalpy of Cu which is not compensated by hydration energy. Why dp transition elements show variable oxidation states? • (i) It is because of presence of unpaired electrons in d-orbitals of transition metal. to Q.47 (ii). (ii) Why is actinoid contraction greater than lanthanoid contraction? (b) Explain the following observations about the transition/inner transition elements: – The word valence is used inconsistently to mean either one or the other. If you are on a personal connection, like at home, you can run an anti-virus scan on your device to make sure it is not infected with malware. The E 0 ( M 2+ / M ) value of a metal depends on the energy changes involved in the formation of the M 2+ ion: (a) (i) EU2+ is strong reducing agent Secondly, in transition elements, incoming electron goes to inner shell (d-orbitals), whereas in main group elements, the incoming electron goes to outermost shell. Lanthanoids show mostly +3 oxidation state. forming unstable intermediates which readily change into products. Answer: to Q.16 (a) (ii). Mon to Sat - 10 AM to 7 PM (iii) Transition metals in general act as good catalysts. (ii) It is because Mn2+ is more stable than Mn3+ due to stable half filled 3d° configuration: In soils, the main source of electrons is carbon atoms of organic matter because carbon has a wide range of oxidation states. (ii) Cr2072 – + 14H+ + 6Fe2+ ———> 2Cr3+ + 7H20 + 6Fe3+. (i) The tendency to show number of oxidation states increases from Sc to Mn and then decreases because number of unpaired electrons increases till Mn, then decreases. The I.E. Answer: (a) (i) Cr2072- + 20H- ——–> 2CrO4– + H2O (iii) It is because 5f, 6d and 7s have comparable energy. Cloudflare Ray ID: 600a3b03883b16ee C. 5f, 6d and 7s levels having comparable energies. (iii) There is a greater range of oxidation states among the actinoids than among the lanthanoids. (i) It is due to lanthanoid contraction which is due to poor shielding effect of f-electrons. (ii) Mn(III) undergoes disproportionation reaction easily. (iii) Refer Ans. (iii) Cu+ ion is not known in aqueous solutions. (b) 3MnO4– + 4H+ ——–> MnO2 + 2MnO4– + 2H2O. (i) Transition metals generally form coloured compounds. (iii) The metal-metal bonding is more frequently found with the second and third series of transition elements. There are 15 known isotopes. (a) Lanthanoids, mostly show +3 oxidation state but some of them show +2 and +4 oxidation states also due to the stability of electronic configuration (4f°, 4f7 and 4f14), e.g. (i) There is in general an increase in density of element from titanium ‘ (Z = 22) to copper (Z = 29). Post author: Post published: December 2, 2020 Post category: Uncategorized Post comments: 0 Comments 0 Comments (b) Write two characteristics of the transition elements. Answer: Why? Refer Ans. The actinoids show in general +3 oxidation state. Actually, i believe its not JUST actinoids, but basically all elements that are period 5 and lower. to Q.59 (ii). (ii) Transition metals form coloured compounds (ii) Chromium is typical hard metal while mercury in liquid, explain. (b) Zinc does not have unpaired electrons and larger in size, therefore, it has weak metallic bonds. (ii) It is due to lanthanoid contraction which is due to poor shielding effect off-electrons, due to which effective nuclear charge increases, therefore, Zr and Hf have almost identical radii. Why? (ii) It is due to maximum number of unpaired electrons(s). (iii) Cobalt (II) is stable in aqueous solution but in the presence of complexing agents, it is easily oxidised. (i) Copper (I) ion is not stable in an aqueous solution. Answer: All of them are soft, have a silvery color (but tarnish in air), and have relatively high density and plasticity. (i) Mn04- (aq) + S2O32-(aq) + H20(l) ——-> (ii) Unlike Cr3+, Mn2+, Fe3+ and the subsequent other M2+ ions of the 3d series of elements, the 4d and the 5d series metals generally do not form stable cationic species. (i) number of oxidation states exhibited (ii) formation of oxometal ions. to Q.41 (ii). Question 38: (iii) Out of Cr3+ and Mn3+, which is a stronger oxidizing agent and why? to Q.67 (ii). (ii) Cu+ ion is not stable in aqueous solutions. 6 d = 6 + 2 = 8. This generally favours higher oxidation states and disfavours low oxidation states in actinides. (iii) Complete the following equation: (a) (i) Refer Ans. Zn+2 salts are white because it does not have unpaired electron, whereas Cu+2 salts are coloured because it has unpaired electron and undergoes d-d transition by absorbing light from visible region and radiate blue colour. (i) Mn(II) ion shows maximum paramagnetic character amongst the bivalent ions of first transition series. (iii) It is due to lanthanoid contraction, effective nuclear charge does not decrease, therefore, atomic size does not increase appreciably in the series of transition metals. (b) What is lanthanoid contraction? 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