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Subject

Chemistry

Chapter

Ch 4The d- and f-Block Elements

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4.1Position in the Periodic TableRead →

4.2Electronic Configurations of the d-Block Elements2 Q

4.3General Properties of the Transition Elements (d-Block)16 Q

4.4Some Important Compounds of Transition ElementsRead →

4.5The LanthanoidsRead →

4.6The Actinoids2 Q

4.7Some Applications of d- and f-Block ElementsRead →

SummaryRead →

NCERT Textbook Exercises38 Q

Answers to Intext QuestionsRead →

NCERT Exemplar71 Q

Q1Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number? (i) 25 (ii) 26 (iii) 27 (iv) 24 Q2The electronic configuration of Cu(II) is 3d⁹ whereas that of Cu(I) is 3d¹⁰. Which of the following is correct? (i) Cu(II) is more stable (ii) Cu(II) is less stable (iii) Cu(I) and Cu(II) are equally stable (iv) Stability of Cu(I) and Cu(II) depends on nature of copper salts Q3Metallic radii of some transition elements are given below. Which of these elements will have highest density? Element: Fe, Co, Ni, Cu Metallic radii/pm: Fe = 126, Co = 125, Ni = 125, Cu = 128 (i) Fe (ii) Ni (iii) Co (iv) Cu Q4Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state? (i) Ag₂SO₄ (ii) CuF₂ (iii) ZnF₂ (iv) Cu₂Cl₂ Q5On addition of small amount of KMnO₄ to concentrated H₂SO₄, a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following. (i) Mn₂O₇ (ii) MnO₂ (iii) MnSO₄ (iv) Mn₂O₃ Q6The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment. (i) 3d⁷ (ii) 3d⁵ (iii) 3d⁸ (iv) 3d² Q7Which of the following oxidation state is common for all lanthanoids? (i) +2 (ii) +3 (iii) +4 (iv) +5 Q8Which of the following reactions are disproportionation reactions? (a) Cu^+ arrow Cu²⁺ + Cu (b) 3MnO₄²⁻ + 4H^+ arrow 2MnO₄^- + MnO₂ + 2H₂O (c) 2KMnO₄ arrow K₂MnO₄ + MnO₂ + O₂ (d) 2MnO₄^- + 3Mn²⁺ + 2H₂O arrow 5MnO₂ + 4H^+ (i) a, b (ii) a, b, c (iii) b, c, d (iv) a, d Q9When KMnO₄ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because (i) CO₂ is formed as the product. (ii) Reaction is exothermic. (iii) MnO₄^- catalyses the reaction. (iv) Mn²⁺ acts as autocatalyst.Q10There are 14 elements in actinoid series. Which of the following elements does not belong to this series? (i) U (ii) Np (iii) Tm (iv) Fm Q11KMnO₄ acts as an oxidising agent in acidic medium. The number of moles of KMnO₄ that will be needed to react with one mole of sulphide ions in acidic solution is (i) (2)/(5) (ii) (3)/(5) (iii) (4)/(5) (iv) (1)/(5)Q12Which of the following is amphoteric oxide? Mn₂O₇, CrO₃, Cr₂O₃, CrO, V₂O₅, V₂O₄ (i) V₂O₅, Cr₂O₃ (ii) Mn₂O₇, CrO₃ (iii) CrO, V₂O₅ (iv) V₂O₅, V₂O₄ Q13Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium? (i) [Xe]4f⁷ 5d¹ 6s² (ii) [Xe]4f⁶ 5d² 6s² (iii) [Xe]4f⁸ 6d² (iv) [Xe]4f⁹ 5s¹ Q14Interstitial 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? (i) They have high melting points in comparison to pure metals. (ii) They are very hard. (iii) They retain metallic conductivity. (iv) They are chemically very reactive.Q15The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of Cr³⁺ ion is ______. (i) 2.87 B.M. (ii) 3.87 B.M. (iii) 3.47 B.M. (iv) 3.57 B.M.Q16KMnO₄ acts as an oxidising agent in alkaline medium. When alkaline KMnO₄ is treated with KI, iodide ion is oxidised to ______. (i) I₂ (ii) IO^- (iii) IO₃^- (iv) IO₄^-Q17Which of the following statements is not correct? (i) Copper liberates hydrogen from acids. (ii) In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine. (iii) Mn³⁺ and Co³⁺ are oxidising agents in aqueous solution. (iv) Ti²⁺ and Cr²⁺ are reducing agents in aqueous solution.Q18When acidified K₂Cr₂O₇ solution is added to Sn²⁺ salts then Sn²⁺ changes to (i) Sn (ii) Sn³⁺ (iii) Sn⁴⁺ (iv) Sn⁺Q19Highest oxidation state of manganese in fluoride is +4 (MnF₄) but highest oxidation state in oxides is +7 (Mn₂O₇) because (i) fluorine is more electronegative than oxygen. (ii) fluorine does not possess d-orbitals. (iii) fluorine stabilises lower oxidation state. (iv) in covalent compounds fluorine can form single bond only while oxygen forms double bond.Q20Although Zirconium belongs to 4d transition series and Hafnium to 5d transition series even then they show similar physical and chemical properties because ______. (i) both belong to d-block. (ii) both have same number of electrons. (iii) both have similar atomic radius. (iv) both belong to the same group of the periodic table.Q21Why is HCl not used to make the medium acidic in oxidation reactions of KMnO₄ in acidic medium? (i) Both HCl and KMnO₄ act as oxidising agents. (ii) KMnO₄ oxidises HCl into Cl₂ which is also an oxidising agent. (iii) KMnO₄ is a weaker oxidising agent than HCl. (iv) KMnO₄ acts as a reducing agent in the presence of HCl.Q22Why does copper not replace hydrogen from acids?Q23Why Eominus values for Mn, Ni and Zn are more negative than expected?Q24Why first ionisation enthalpy of Cr is lower than that of Zn?Q25Transition elements show high melting points. Why?Q26When Cu²⁺ ion is treated with KI, a white precipitate is formed. Explain the reaction with the help of chemical equation.Q27Out of Cu₂Cl₂ and CuCl₂, which is more stable and why?Q28When a brown compound of manganese (A) is treated with HCl it gives a gas (B). The gas taken in excess, reacts with NH₃ to give an explosive compound (C). Identify compounds A, B and C.Q29Although fluorine is more electronegative than oxygen, but the ability of oxygen to stabilise higher oxidation states exceeds that of fluorine. Why?Q30Although Cr³⁺ and Co²⁺ ions have same number of unpaired electrons but the magnetic moment of Cr³⁺ is 3.87 B.M. and that of Co²⁺ is 4.87 B.M. Why?Q31Ionisation enthalpies of Ce, Pr and Nd are higher than Th, Pa and U. Why?Q32Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?Q33Although +3 oxidation state is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?Q34Explain why does colour of KMnO₄ disappear when oxalic acid is added to its solution in acidic medium.Q35When orange solution containing Cr₂O₇²⁻ ion is treated with an alkali, a yellow solution is formed and when H^+ ions are added to yellow solution, an orange solution is obtained. Explain why does this happen?Q36A solution of KMnO₄ 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?Q37The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?Q38Eominus of Cu is +0.34V while that of Zn is -0.76V. Explain.Q39The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?Q40While filling up of electrons in the atomic orbitals, the 4s orbital is filled before the 3d orbital but reverse happens during the ionisation of the atom. Explain why?Q41Reactivity of transition elements decreases almost regularly from Sc to Cu. Explain.Q42Identify A to E and also explain the reactions involved. (The Exemplar gives the following reaction scheme:) CuCO₃ gives CuO on one branch and gas (D) on the other. Left branch: CuO, on heating with CuS, gives (A); (A) with HNO₃ (conc.) gives (B); (B) with NH₃ (aq.) gives (C), a blue solution. Right branch: (D) with Ca(OH)₂ gives (E), which appears milky; (E) with CO₂ gives Ca(HCO₃)₂, a clear solution.Q43When a chromite ore (A) is fused with sodium carbonate in free excess of air and the product is dissolved in water, a yellow solution of compound (B) is obtained. After treatment of this yellow solution with sulphuric acid, compound (C) can be crystallised from the solution. When compound (C) is treated with KCl, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reactions.Q44When an oxide of manganese (A) is fused with KOH in the presence of an oxidising agent and dissolved in water, it gives a dark green solution of compound (B). Compound (B) disproportionates in neutral or acidic solution to give purple compound (C). An alkaline solution of compound (C) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds A to D and also explain the reactions involved.Q45On the basis of Lanthanoid contraction, explain the following: (i) Nature of bonding in La₂O₃ and Lu₂O₃. (ii) Trends in the stability of oxo salts of lanthanoids from La to Lu. (iii) Stability of the complexes of lanthanoids. (iv) Radii of 4d and 5d block elements. (v) Trends in acidic character of lanthanoid oxides.Q46(a) Answer the following questions: (i) Which element of the first transition series has highest second ionisation enthalpy? (ii) Which element of the first transition series has highest third ionisation enthalpy? (iii) Which element of the first transition series has lowest enthalpy of atomisation? (b) Identify the metal and justify your answer. (i) Carbonyl M(CO)₅ (ii) MO₃F Q47Mention the type of compounds formed when small atoms like H, C and N get trapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.Q48(a) Transition metals can act as catalysts because these can change their oxidation state. How does Fe(III) catalyse the reaction between iodide and persulphate ions? (b) Mention any three processes where transition metals act as catalysts.Q49A violet compound of manganese (A) decomposes on heating to liberate oxygen and compounds (B) and (C) of manganese are formed. Compound (C) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C) with conc. H₂SO₄ and NaCl, chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds A to D and also explain the reactions involved.Q50Generally transition elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured? (i) KMnO₄ (ii) Ce(SO₄)₂ (iii) TiCl₄ (iv) Cu₂Cl₂ Q51Transition 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? (i) Co²⁺ (ii) Cr²⁺ (iii) Mn²⁺ (iv) Cr³⁺Q52In the form of dichromate, Cr(VI) is a strong oxidising agent in acidic medium but Mo(VI) in MoO₃ and W(VI) in WO₃ are not because ______. (i) Cr(VI) is more stable than Mo(VI) and W(VI). (ii) Mo(VI) and W(VI) are more stable than Cr(VI). (iii) Higher oxidation states of heavier members of group-6 of transition series are more stable. (iv) Lower oxidation states of heavier members of group-6 of transition series are more stable.Q53Which of the following actinoids show oxidation states upto +7? (i) Am (ii) Pu (iii) U (iv) Np Q54General electronic configuration of actinoids is (n-2)f¹⁻¹⁴(n-1)d⁰⁻²ns². Which of the following actinoids have one electron in 6d orbital? (i) U (Atomic no. 92) (ii) Np (Atomic no. 93) (iii) Pu (Atomic no. 94) (iv) Am (Atomic no. 95)Q55Which of the following lanthanoids show +2 oxidation state besides the characteristic oxidation state +3 of lanthanoids? (i) Ce (ii) Eu (iii) Yb (iv) Ho Q56Which of the following ions show higher spin only magnetic moment value? (i) Ti³⁺ (ii) Mn²⁺ (iii) Fe²⁺ (iv) Co³⁺Q57Transition elements form binary compounds with halogens. Which of the following elements will form MF₃ type compounds? (i) Cr (ii) Co (iii) Cu (iv) Ni Q58Which of the following will not act as oxidising agents? (i) CrO₃ (ii) MoO₃ (iii) WO₃ (iv) CrO₄²⁻Q59Although +3 is the characteristic oxidation state for lanthanoids but cerium also shows +4 oxidation state because ______. (i) it has variable ionisation enthalpy (ii) it has a tendency to attain noble gas configuration (iii) it has a tendency to attain f⁰ configuration (iv) it resembles Pb⁴⁺Q60Match the catalysts given in Column I with the processes given in Column II. Column I (Catalyst): (i) Ni in the presence of hydrogen (ii) Cu₂Cl₂ (iii) V₂O₅ (iv) Finely divided iron (v) TiCl₄ + Al(CH₃)₃ Column II (Process): (a) Zieglar Natta catalyst (b) Contact process (c) Vegetable oil to ghee (d) Sandmeyer reaction (e) Haber's Process (f) Decomposition of KClO₃ Q61Match the compounds/elements given in Column I with uses given in Column II. Column I (Compound/element): (i) Lanthanoid oxide (ii) Lanthanoid (iii) Misch metal (iv) Magnesium based alloy is constituent of (v) Mixed oxides of lanthanoids are employed Column II (Use): (a) Production of iron alloy (b) Television screen (c) Petroleum cracking (d) Lanthanoid metal + iron (e) Bullets (f) In X-ray screen Q62Match the properties given in Column I with the metals given in Column II. Column I (Property): (i) An element which can show +8 oxidation state (ii) 3d block element that can show upto +7 oxidation state (iii) 3d block element with highest melting point Column II (Metal): (a) Mn (b) Cr (c) Os (d) Fe Q63Match the statements given in Column I with the oxidation states given in Column II. Column I: (i) Oxidation state of Mn in MnO₂ is (ii) Most stable oxidation state of Mn is (iii) Most stable oxidation state of Mn in oxides is (iv) Characteristic oxidation state of lanthanoids is Column II: (a) +2 (b) +3 (c) +4 (d) +5 (e) +7 Q64Match the solutions given in Column I and the colours given in Column II. Column I (Aqueous solution of salt): (i) FeSO₄.7H₂O (ii) NiCl₂.4H₂O (iii) MnCl₂.4H₂O (iv) CoCl₂.6H₂O (v) Cu₂Cl₂ Column II (Colour): (a) Green (b) Light pink (c) Blue (d) Pale green (e) Pink (f) Colourless Q65Match the property given in Column I with the element given in Column II. Column I (Property): (i) Lanthanoid which shows +4 oxidation state (ii) Lanthanoid which can show +2 oxidation state (iii) Radioactive lanthanoid (iv) Lanthanoid which has 4f⁷ electronic configuration in +3 oxidation state (v) Lanthanoid which has 4f¹⁴ electronic configuration in +3 oxidation state Column II (Element): (a) Pm (b) Ce (c) Lu (d) Eu (e) Gd (f) Dy Q66Match the properties given in Column I with the metals given in Column II. Column I (Property): (i) Element with highest second ionisation enthalpy (ii) Element with highest third ionisation enthalpy (iii) M in M(CO)₆ is (iv) Element with highest heat of atomisation Column II (Metal): (a) Co (b) Cr (c) Cu (d) Zn (e) Ni Q67Assertion: Cu²⁺ iodide is not known. Reason: Cu²⁺ oxidises I^- to iodine. (i) Both assertion and reason are true, and reason is the correct explanation of the assertion. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion. (iii) Assertion is not true but reason is true. (iv) Both assertion and reason are false.Q68Assertion: Separation of Zr and Hf is difficult. Reason: Because Zr and Hf lie in the same group of the periodic table. (i) Both assertion and reason are true, and reason is the correct explanation of the assertion. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion. (iii) Assertion is not true but reason is true. (iv) Both assertion and reason are false.Q69Assertion: Actinoids form relatively less stable complexes as compared to lanthanoids. Reason: Actinoids can utilise their 5f orbitals along with 6d orbitals in bonding but lanthanoids do not use their 4f orbital for bonding. (i) Both assertion and reason are true, and reason is the correct explanation of the assertion. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion. (iii) Assertion is not true but reason is true. (iv) Both assertion and reason are false.Q70Assertion: Cu cannot liberate hydrogen from acids. Reason: Because it has positive electrode potential. (i) Both assertion and reason are true, and reason is the correct explanation of the assertion. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion. (iii) Assertion is not true but reason is true. (iv) Both assertion and reason are false.Q71Assertion: The highest oxidation state of osmium is +8. Reason: Osmium is a 5d-block element. (i) Both assertion and reason are true, and reason is the correct explanation of the assertion. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion. (iii) Assertion is not true but reason is true. (iv) Both assertion and reason are false.

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