Free Ncert Solutions for 12th Class Chemistry The d-and f-Block Elements

1) Silver atom has completely filled d-orbitals (4d10) in its ground state. How can you say that it is a transition element?

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2) In the series Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomisation of zinc is the lowest i.e. 126 kJ mol–1. Why?

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3) Which is the 3d series of the transition metals exhibits the largest number of oxidation states and why?

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4) The value for copper is positive (+0.34 V). What is possible the reason for this?

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5) How would you account for irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?

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6) Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

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7) Which is a stronger reducing agent, Cr2+ or Fe2+ and why?

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8) Calculate the 'spin only' magnetic moment of ion (Z = 27).

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9) Explain why Cu+ ion is not stable in aqueous solutions?

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10) Actinoid contraction is greater from element to than lanthanoid contraction. Why?

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11) Write down the electronic configuration of (a) (b) (c) (d) (e) (f) (g) (h)

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12) Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their +3 state ?

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13) Explain briefly how +2 oxidation state becomes more and more stable in the first half of the first row transition elements with increasing atomic number.

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14) To what extent do the electronic configurations decide the stability or oxidation states in the first series of the transition elements? Illustrate your answer with an example.

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15) What must be the stable oxidation state of the transition elements with the following electronic configuration in the ground states or their atoms: 3d3, 3d5, 3d8, 3d4?

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16) Name the oxometal anions in the first transition series of transition metals in which the metal exhibits oxidation state equal to its group number.

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17) What is lanthanoid contraction? What are the consequences of lanthanoid contraction?

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18) What are the characteristics of transition elements and why are they called transition elements? Which of the d-block elements may not be regarded as the transition elements?

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19) In what way is the electronic configuration of the transition elements different from that of the non-transation elements?

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20) What are the different oxidation states exhibited by the lanthanoids?

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21) Explain giving reasons : (a) Transition metals and many of their compounds show paramagnetic behaviour. (b) Transition metals have high enthalpy of atomisation. (c) The transition metals generally form coloured compounds. (d) Transitional metals and their many compounds act as good catalysts.

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22) What are interstitial compounds? Why are such compounds well known for transition metals?

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23) How is variability in oxidation states of transition metals different from that of non-transition metals? Illustrate with examples.

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24) Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?

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25) Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with : (a) iodide (b) iron (iii) solution (c) H2S.

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26) Describe the preparation of potassium permanganate. How does the acidified permanganate solution reacts with : (i) iron (ii) ions (iii) SO2 (iv) oxalic acid ? Write the ionic equations for the reactions.

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27) For M2+/M and M3 + /M2+ systems, the values of some metals are given : Use this data to comment upon: (a) The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+. (b) The ease with which iron can be oxidised as compared to the similar process for either chromium or manganese metal.

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28) Predict which of the following will be coloured in aqueous solution? Ti3+, V3+, Cu+, Sc3+, Mn2+ , Fe3+ and Co2+ Give reason for each.

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29) Compare the stability of +2 oxidation state for the elements of the first transition series.

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30) Compare the chemistry of actinoids with that of lanthanoids with special reference to (i) Electronic configuration (ii) Atomic and ionic sizes (iii) Oxidation state (iv)Chemical reactivity.

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31) How would you account for the following (a) Of the d4 species, Cr2+ is strongly reducing while Mn3+ is strongly oxidising in nature. (b) Cobalt (II) is stable in aqueous solution but in the presence of complexing reagents, it is easily oxidised. (c) The d1 configuration is very unstable in ions.

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32) What are disproportionation reactions? Give two examples.

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33) Which metal in the first transition metal series exhibits +1 oxidation state most frequently and why?

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34) Calculate the number of unpaired electrons in the following gaseous ions : Mn3+, Cr3+, V3+ and Ti3+ Which one of these is most stable in aqueous solution?

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35) Give example and suggest reasons for the following features of transition metal chemistry: (a) The lowest oxide of the transition metal is basic while the highest is acidic. (b) A transition metal exhibits higher oxidation states in oxides and fluorides. (c) The highest oxidation state is exhibited in oxoanions of a metal.

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36) Indicate the steps in the preparation of: (a) K2Cr2O7 from chromite ore. (b) KMnO4 from pyrolusite ore.

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37) What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.

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38) What are inner transition elements? Decide which or the following atomic numbers belong to inner transition elements : 29, 59, 74, 95, 102, 104

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39) The chemistry of actinoid elements is not so smooth as that of lanthanoids. Justify this statement by giving some examples from the oxdiation states of these elements.

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40) Which is the last element in the series of actinoids? Write the electronic configuration of the element. Comment upon the possible oxidation state.

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41) Use Hand's rule to derive the electron configuration of Ce3+ ion and calculate it, magnetic moment on the basis of spin-only formula.

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42) Name the members of lanthanoid series which exhibit +4 oxidation states and those which exhibit +2 oxidation states. Try to correlate this type of behaviour with the electronic configuration of these elements.

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43) Compare the chemistry of the actinoids with that of lanthanoids with reference to : (i) Electronic configuration (ii) Oxidation states (iii) Chemical reactivity.

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44) Write the electronic configuration of the elements with atomic numbers 61, 91, 101, 109.

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45) Compare the general characteristics of the first series of transition metals with those of those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points : (i) electronic configurations, (ii) oxidation states, (iii) ionisation enthalpies and (iv) atomic sizes.

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46) Write down the number or 3d electrons in each or the following ions :Ti2+, V2+, Cr3+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+ and Cu2+.Indicate how would you expect the rive 3d orbitals to be occupied for these hydrated ions (octahedral).

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47) Comment on the statement that the elements of the first transition series possess many properties different from those of heavier transition elements

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48) What can be inferred from the magnetic moment of the following complex species Example Magnetic moment (BM) K4[Mn(CN)6] 2.2 [Fe(H2O)6]2+ 5.3 K2 [MnCl4] 5.9

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49) Electronic configuration of a transition element X in +3 oxidation state is what is its atomic number? (a) 25 (b) 26 (c) 27 (d) 24

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50) The electronic configuration of (II) is where as that of (l) is Which of the following is correct? (a) Cu (II) is more stable (b) Cu (ll) is less stable (c) Cu (l) and Cu (ll) are equally stable (d) Stability of Cu (l) and Cu(ll) depends on nature of copper salts

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51) Metallic radii of some transition elements are given below. Which of these elements will have highest density?

Element	Fe	Co	Ni	Cu
Metallic radii/pm	126	125	125	128

(a) Fe (b)Ni (c) Co (d) Cu

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52) Generally, transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state? (a) (b) (c) (d)

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53) On addition of small amount of to concentrated H 2804, a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following. (a) (b) (c) (d)

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54) The magnetic, nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, .which shows highest magnetic moment. (a) 3d7 (b) 3d5 (c) 3d8 (d) 3d2

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55) Which of the following oxidation state is common for all lanthanoids? (a) +2 (b) +3 (c) +4 (d) +5

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56) Which of the following reactions are disproportionation reactions? (i) (ii) (iii) (iv) (a) (i) (b) (i), (ii) and (iii) (c) (ii), (iii) and (iv) (d) (i) and (iv)

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57) When solution is added to oxalic add solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because (a) is formed as the product (b) reaction is exothermic (c) catalyses the reaction (d) acts as autocatalyst

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58) There are 14 elements in actinoid series. Which of the following elements does not belong to this series? (a) U (b) Np (c) Tm (d) Fm

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59) acts as an oxidising agent in acidic medium. The number of moles of that will be needed to react with one mole of sulphide ions in acidic solution is (a) (b) (c) (d)

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60) Which of the following is amphoteric oxide? (a) (b) (c) (d)

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61) Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium? (a) (b) (c) (d)

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62) Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds? (a)They have high melting points in comparison to pure metals (b) They are very hard (c) They retain metallic conductivity (d) The are chemically very reactive

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63) The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of ion is (a) 2.87BM (b) 3.87 BM (c) 3.47BM (d) 3.57BM

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64) acts as an oxidising agent in alkaline medium. When alkaline KMn04 is treated with KI, iodide ion is oxidised to.......... (a) (b) (c) (d)

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65) Which of the following statements is not correct? (a) Copper liberates hydrogen from acids (b) In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine (c) and are oxidising agents in aqueous solution (d) and are reducing agents in aqueous solution

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66) When acidified solution is added to salt then changes to (a) (b) (c) (d)

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67) Highest oxidation state of manganese in fluoride is +4 but highest oxidation state in oxides is +7 because (a) fluorine is more electronegative than oxygen (b) fluorine does not possess d orbitals (c) fluorine stabilises lower oxidation state (d) in covalent compounds, fluorine can form single bond only while oxygen forms double bond

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68) Although zirconium belongs to transition series and hafniun to transition series even then they show similar physical and chemical properties because.............. (a) both belong to d - block (b) both have same number of electrons (c) both have similar atomic radius (d) both belong to the same group of the Periodic Table

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69) Why is HCl not used to make the medium acidic in oxidation reactions of in acidic medium? (a) Both HCl and act as oxidising agents (b) oxidises HCl into which is also an oxidising agent (c) is a weaker oxidising agent than HCl (d) acts as a reducing agent in the presence of HCl

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70) Generally transition elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured? (a) (b) (c) (d)

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71) Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment? (a) (b) (c) (d)

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72) In the form of dichromate, Cr () is a strong oxidising agent in acidic medium but Mo (VI) in and W() in are not because (a) Cr (VI) is more stable than Mo() and W(VI). (b) Mo (VI) and W (VI) are more stable than Cr (VI). (c) Higher oxidation states of heavier members of group 6 of transition series are more stable. (d) Lower oxidation states of heavier members of group-6 of transition series are more stable.

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73) Which of the following actinoids show oxidation states upto +7? (a) Am (b) Pu (c) U (d) Np

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74) General electronic configuration of actinoids is Which of the following actinoids have one electron in 6d orbital? (a) U (Atomic number. 92) (b) Np (Atomic number. 93) (c) Pu (Atomic number. 94) (d) Am (Atomic number. 95)

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75) Which of the following lanthanoids show +2 oxidation state besides the characteristic oxidation state +3 of lanthanoids? (a) Ce (b) Eu (c) Yb (d) Ho

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76) Which of the following ions show higher spin only magnetic moment value? (a) (b) (c) (c)

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77) Transition elements form binary compounds with halogens. Which of the following elements will form Mf^ type compounds? (a) Cr (b) Co (c) Cu (d) Ni

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78) Which of the following will not act as oxidising agents? (a) (b) (c) (d)

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79) Although +3 is the characteristic oxidation state for lanthanoids but cerium also shows+4 oxidation state because (a) it has variable ionisation enthalpy (b) it has a tendency to attain noble gas configuration (c) it has a tendency to attain configuration (d) it resembles

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80) Why does copper not replace hydrogen from acids?

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81) Why values for Mn, Ni and Zn are more negative than expected?

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82) Why first ionisation enthalpy of Cr is lower than that of Zn?

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83) Transition elements show high melting points. Why?

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84) When ion is treated with KI, a white precipitate is formed. Explain the reaction with the help of chemical equation.

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85) Out of and , which is more stable and why?

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86) When a brown compound. of manganese (A) is treated with HCL it gives a gas (B). The gas taken in excess, reacts with to give an explosive compound (C) Identify compounds A, B and C.

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87) Although fluorine is more electronegative than oxygen, but the ability of oxygen to stabilise higher oxidation states exceeds that of fluorine. Why?

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88) Although and ions have same number of unpaired electrons but the magnetic moment of is 3.87 BM and that of is 4.87 BM, Why?

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89) lonisation enthalpies of Ce, Pr and Nd are higher than Th, Pa and U. Why?

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90) Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?

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91) Although +3 oxidation states is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?

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92) Explain, why does colour of disappear when oxalic acid is added to its solution in acidic medium?

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93) When orange solution containing ion is treated with an alkali, a yellow solution is formed and when ions are added to yellow solution, an orange solution is obtained. Explain why does this happen?

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94) A solution of on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?

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95) The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain, why?

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96) of Cu is +0.34V while that of Zn is -0.76 V. Explain.

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97) The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?

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98) While filling up of electrons in the atomic orbitals, the As orbital is filled before the 3d orbital but reverse happens during the ionisation of the atom. Explain why?

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99) Reactivity of transition elements decreases almost regularly from Se to Cu. Explain.

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100) Match the catalysts given in Column I with the processes given in Column II.

	Column I (Catalyst)	Column II (Process)
A.	Ni in the presence of hydrogen	1. Ziegler-Natta catalyst
B.		2. Contact process
C		3. Vegetable oil to ghee
D.	Finely divided iron	4. Sandmeyer reaction
E.		5. Haber's process
		6. Decomposition of

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101) Match the compounds/elements given in Column I with uses given in Column II.

Column 1 (Compound/element)	Column 11 (Use)
A. Lanthanoid oxide B. Lanthanoid C. Misch metall D. Magnesium based alloy is constituent of E. Mixed oxides of lanthanoids are employed	1. Production of iron alloy 2. Television screen 3. Petroleum cracking 4. Lanthanoid metal + iron 5. Bullets 6. X-ray screen

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102) Match the properties given in Column I with the metals given in Column II.

Column 1 (Property)	Column 11 (Metal)
A. An element which can show+8 oxidation state B. 3d block element that can show upto +7 oxidation state C. 3d block element with highest melting point	1. Mn 2. Cr 3. Os 4. Fe

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103) Match the statements given in Column I with the oxidation states given in Column II.

	Column 1	Column 11
A.	Oxidation state of Mn in is	1. +2
B.	Most stable oxidation state of Mn is	2. +3
C.	Most stable oxidation state of Mn in oxides is	3. +4
D.	Characteristic oxidation state of lanthanoids is	4. +5
		5. +7

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104) Match the solutions given in Column I and the colours given in Column II.

Column 1 (Aqueous solution of salt)	Column 11 (Colour)
A.	1. Green
B.	2. Light pink
C.	3. Blue
D.	4. Pale green
E.	5. Pink
	6. Colourless

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105) Match the property given in Column I with the element given in Column II.

	Column I (Property)	Column II (Element)
A.	Lanthanoid which shows + 4 oxidation state	1. Pm
B.	Lanthanoid which can show +2 oxidation state	2. Ce
C.	Radioactive lanthanoid	3. Lu
D.	Lanthanoid which has electronic	4. Eu
	configuration in +3 oxidation state
E.	Lanthanoid which has electronic configuration in +3 oxidation state	5. Gd
		6. Dy

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106) Match the properties given in Column I with the metals given in Column II.

Column 1 (Property)	Column 11 (Metal)
A. Element with highest second ionisation enthalpy B. Element with highest third ionisation enthalpy C. M in D. Element with highest heat of atomisation	1. Col 2. Cr 3. Cu, 4. Zn 5. Ni