The d- and f-Block Elements quiz

The electronic configuration of Cr (Z = 24) is:

Which ion is colourless?

The highest oxidation state shown by manganese is:

Zr and Hf have almost identical atomic radii because of:

The catalyst used in the contact process for sulphuric acid is:

In acidic medium, MnO4- is reduced to:

The common oxidation state of lanthanoids is:

Which 3d metal has a positive E0(M2+/M) value?

The number of unpaired electrons in Fe3+ is:

When an acid is added to a yellow chromate solution, it turns:

Why do transition metals form coloured compounds? (2 marks)

Why do transition metals and their compounds act as good catalysts? (2 marks)

Why is the enthalpy of atomisation of transition metals high? (2 marks)

Why is Cu+ unstable in aqueous solution? (2 marks)

Why do transition metals form alloys easily? (2 marks)

Write the equation for the disproportionation of manganate ion in acidic medium. (2 marks)

Why is Ce4+ a good oxidising agent and Eu2+ a good reducing agent? (2 marks)

Why do actinoids show a wider range of oxidation states than lanthanoids? (2 marks)

Why are Mn2+ compounds more stable than Fe2+ compounds towards oxidation to the +3 state? (2 marks)

Write the ionic equation for the oxidation of oxalate ion by permanganate in acidic medium. (2 marks)

Calculate the spin-only magnetic moment of a divalent ion of an element with atomic number 26 in aqueous solution (sqrt(24) = 4.90). (3 marks)

Calculate the volume of 0.05 M K2Cr2O7 needed to oxidise 30 mL of 0.1 M Fe2+ solution in acidic medium. (3 marks)

Calculate the mass of KMnO4 (molar mass 158) required to oxidise 0.5 mol of Fe2+ in acidic medium. (3 marks)

A transition metal ion has a magnetic moment of 3.87 BM. Calculate the number of unpaired electrons and suggest one ion of the 3d series that has this value. (3 marks)

Calculate the volume of 0.02 M KMnO4 required to react completely with 50 mL of 0.1 M oxalic acid in acidic medium. (3 marks)

Read the passage and answer the questions. In a school lab, a student titrated Mohr's salt solution against KMnO4 in the presence of dilute H2SO4. The purple colour disappeared on each addition until the end point, when a permanent pale pink colour appeared. (i) Write the ionic equation for the reaction. (ii) Why is no external indicator needed? (iii) Why is HCl not used instead of H2SO4? (5 marks)

Read the passage and answer the questions. A breath analyser used to detect alcohol in drivers contains acidified potassium dichromate. The orange colour changes to green when alcohol is present in the breath. (i) Explain the colour change. (ii) Write the half reaction for dichromate. (iii) What is the oxidation state of Cr before and after the reaction? (5 marks)

Read the passage and answer the questions. The atomic radii of the second and third transition series elements are almost the same, for example Zr (160 pm) and Hf (159 pm). This makes their separation very difficult. (i) Name the phenomenon responsible. (ii) Explain its cause. (iii) State one other consequence. (5 marks)

Read the passage and answer the questions. In the Haber process, iron is used as a catalyst, and in the hydrogenation of vegetable oils, finely divided nickel is used. Ziegler-Natta catalyst, TiCl4 with Al(CH3)3, is used for making polythene. (i) Why are transition metals good catalysts? (ii) Why is the catalyst used in finely divided form? (iii) Name one other industrial process with a transition metal catalyst. (5 marks)

Read the passage and answer the questions. Potassium permanganate is prepared by fusing pyrolusite with KOH in the presence of an oxidising agent, forming a green compound, which is then oxidised electrolytically to give purple crystals. (i) Name the green compound and give its formula. (ii) Write the equations. (iii) State two uses of KMnO4. (5 marks)

Explain the general characteristics of transition elements: atomic radii, ionisation enthalpy, oxidation states and magnetic properties, with graphs where appropriate. (6 marks)

Describe the preparation of K2Cr2O7 from chromite ore with equations. Draw the structures of chromate and dichromate ions, and explain its oxidising action. (6 marks)

Describe the preparation of KMnO4 from pyrolusite with equations. Draw the structures of manganate and permanganate ions, and explain its oxidising action in acidic, neutral and alkaline media. (6 marks)

Explain lanthanoid contraction, its causes and consequences. Draw a graph showing the decrease in ionic radii of Ln3+ ions across the series. (6 marks)

Compare lanthanoids and actinoids. Draw a chart showing differences in configuration, oxidation states, radioactivity and complex formation. (6 marks)