The d and f Block Elements
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7. (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.
7. (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.
7. (A) 2I- + S2O82- →Fe (III) I2 + 2SO42-
role of fe ions:
2Fe3+ + 2I- → 2Fe2+ + I2
2Fe2+ + S2O82- → 2Fe3+ + 2SO42-
(B) 1. Fine powdered state of Nick
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6. Mention the type of compounds formed when small atoms like H get trapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.
6. Mention the type of compounds formed when small atoms like H get trapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.
6. Interstitial compounds are formed when small atoms like H, C and N get trapped inside the crystal lattice of transition metals.
Characteristics:
They are hard and rigid in nature having high melting points.
Like pure metals only, they are conductors. They can gain chemical inertness.
Upvote 5. (A) Answer the following questions:
(i) Which element of the first transition series has the highest second ionization enthalpy?
(ii) Which element of the first transition series has highest third ionization enthalpy?
(iii) Which element of the first transition series has lowest enthalpy of atomization?
(B) Identify the metal and justify your answer:
(i) CarbonylmM(CO)5
(ii) MO3F
5. (A) Answer the following questions:
(i) Which element of the first transition series has the highest second ionization enthalpy?
(ii) Which element of the first transition series has highest third ionization enthalpy?
(iii) Which element of the first transition series has lowest enthalpy of atomization?
(B) Identify the metal and justify your answer:
(i) CarbonylmM(CO)5
(ii) MO3F
5. (A) (i) Out of all the elements of the first transition series copper has the highest second ionisation enthalpy.
Electronic configuration of Copper is: 3d104s1
After the Loss of first electron from the 4s copper acquires 3d10 configuration which is stable. Therefore, removal of second electron fro
Upvote 4. On the basis of lanthanoid contraction, explain the following:
(a) Nature of bonding in La2O3 and Lu2O3.
(b) Trends in the stability of oxo-salts of lanthanoids from La to Lu.
(c) Stability of the complexes of lanthanides.
(d) Radii of 4d- and 5d-block elements.
(e) Trends in acidic character of lanthanide oxides.
4. On the basis of lanthanoid contraction, explain the following:
(a) Nature of bonding in La2O3 and Lu2O3.
(b) Trends in the stability of oxo-salts of lanthanoids from La to Lu.
(c) Stability of the complexes of lanthanides.
(d) Radii of 4d- and 5d-block elements.
(e) Trends in acidic character of lanthanide oxides.
4. (a) As per fajan's rule, smaller the size of ion, greater is its tendency to make covalent bonds as the positively charged cation strongly attract the negatively charged electron cloud.
On moving from La to Lu in the lanthanoid series, the atomic size decreases so the covalent character increases.
Upvote 4. On the basis of lanthanoid contraction, explain the following:
(a) Nature of bonding in La2O3 and Lu2O3.
4. On the basis of lanthanoid contraction, explain the following:
(a) Nature of bonding in La2O3 and Lu2O3.
4. As per fajan's rule, smaller the size of ion, greater is its tendency to make covalent bonds as the positively charged cation strongly attract the negatively charged electron cloud.
On moving from La to Lu in the lanthanoid series, the atomic size decreases so the covalent character increases
Upvote 3. When an oxide of manganese (A) is fused with KOH in the presence of an oxidizing agent and dissolved in water, it gives a dark green solution of compound (B). Compound (B) disproportionate 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.
3. When an oxide of manganese (A) is fused with KOH in the presence of an oxidizing agent and dissolved in water, it gives a dark green solution of compound (B). Compound (B) disproportionate 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.
3. (A) = MnO2
(B) = K2MnO4
(C) = KMnO4
(D) = KIO3
2MnO2 + 4KOH + O2 → 2K2MnO4 + 2H2O
(A)
Upvote 2. When 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 crystallized from the solution. When compound (C) is treated with ?, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reactions.
2. When 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 crystallized from the solution. When compound (C) is treated with ?, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reactions.
2. (A) = FeCr2O4
(B) = Na2CrO4
(C) = Na2Cr2O7
(D) = K2Cr2O7
4FeCrO4 + 8NaCO3 + 7O2 → 8Na2CrO4 + 2Fe2O3 + 8CO2
(A)
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1. CuCO3 
CuO + CO2
(D)
Ca (OH)2 + CO2 → CaCO3 + H2O
(E)
CaCO3 + CO2 + H2O → Ca (HCO3)2
&nb
Upvote How do i identify the Class 12 Chemistry Chapter 4 important questions?
How do i identify the Class 12 Chemistry Chapter 4 important questions?
Students need to practice the Class 12 Chemistry previous year question to identify the important questions. Some of important questions are reactions of and in acidic, basic, and neutral medium, lanthanide contraction and its consequences, balancing redox reactions, etc.
Upvote What is the benefit of the previous year questions of d- and f-block class 12 pdf?
What is the benefit of the previous year questions of d- and f-block class 12 pdf?
Students can use the class 12 previous year d and f block questions pdf to prepare for the exam and self-assessment. NCERT solutions enhace the proble sloving skills by explaning the complex questions in easy way.
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