Chemistry Worksheets Class 12 on Chapter 8: The d & f Block Elements with Answers - Set 4

D block elements are the elements that can be found from the third group to the twelfth group of the modern periodic table. The valence electrons of these elements fall under the d orbital. D block elements are also referred to as transition elements or transition metals.

• 3d- Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn
• 4d- Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd
• 5d- La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg
• 6d- incomplete.

F block elements are divided into two series, namely lanthanoids and actinoids. This block of elements are often referred to as inner transition metals because they provide a transition in the 6th and 7th row of the periodic table which separates the s block and the d block elements.

• Lanthanide series or 4f series (Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm , Yb)
• Actinide series of 5f series ( Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, Mo)

Download Class 12 chemistry Chapter 8 The d & f Block Elements PDF – Set 4

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CBSE Class 12 Chemistry Chapter 8 The d & f Block Elements Worksheet – Set 4

Q1. Transition elements show positive oxidation state, generally due to:

a.) large atomic size

b.) low ionization energy

c.) low electronegativity

d.) high electronegativity

Q2. Which of the following oxidation state is common for all lanthanoids?

a.) +2

b.) +3

c.) +4

d.) +5

Q3. 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

Q4. When acidifies K₂Cr₂O₇ solution is added to Sn²²⁺ salts then Sn²⁺ changes to-

a.) Sn

b.) Sn³⁺

c.) Sn⁴⁺

d.) Sn⁺

Q5. The stable oxidation state of Ce is-

a.) +4

b.) +3

c.) +2

d.) +5

Q6. Name an important alloy which contains some of the lanthanoid metals.

Q7. Which metal in the first transition series exhibits a +1 oxidation state most frequently and why?

Q8. Chromium is a typical hard metal while mercury is a liquid.

Q9. Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?

Q10. Why is europium (II) more stable than cerium (II)?

Q11. In the series Sc(Z=21) to Zn (Z=20), the enthalpy of zinc is the lowest (126 kJ mol^–1). Why?

Q12. What may be the stable oxidation state of the transition element with the following d-electron configurations in the ground state of their atoms: 3d³, 3d⁵, 3d⁸, and 3d⁴?

Q13.Complete the following chemical equations:

i.) Cr₂O₇^2– + 6Fe²⁺ + 14H⁺ →

ii.) 2CrO₄^2– + 2H⁺ →

iii.) 2MnO₄^2– + 5C₂O₄^2– + 16H⁺ →

Q14. i.) E° value for (Mn²⁺ | Mn) is negative whereas for (Cu²⁺ | Cu) is positive.

ii.) Actinoids show irregularities in their electronic configuration.

Q15. Write chemical equations for the following reactions:

a.) Oxidation of nitrite ion by MnO₄^– in acidic medium.

b.) Acidification of potassium chromate solution.

c.) Disproportionation of manganese (VI) in acidic solution.

Q16. Explain why transition elements form coloured compounds?

Q17.

i.) Does actinoids show actinoid contraction similar to lanthanoid contraction?

ii.) Arrange Ce³⁺ (Z = 58), Sm³⁺ (Z = 62) and Yb³⁺ (Z = 70) in decreasing order of ionic radii.

iii.) Name the basic cause of similar atomic radii of Hf and Zr

iv.) Name two tripositive lanthanoid ions which are colourless.

Q18.

a.) What are the different oxidation states exhibited by lanthanoids?

b.) Which trivalent ion has maximum size in lanthanoid series?

Q19. Account for the following:

i.) The metallic radii of the third (5d) series of transition metals are virtually the same as those of the corresponding group members of the second (4d) series.

ii.) Lanthanoids form primarily +3 ions, white the actinoids usually have higher oxidation states in their compounds, +4 or even +6 being typical.

iii.) Among lanthanoids, Ln (III) compounds are predominant. However, occasionally in solutions or in solid compounds, +2 and +4 ions are also obtained.

Q20. Explain the following:

(i) Out of Sc³⁺, Co²⁺, and Cr³⁺ ions, only Sc³⁺ is colorless in aqueous solutions.

(Atomic no.: Co = 27; Sc = 21 and Cr = 24)

(iI) The E° Cu²⁺/Cu for copper metal is positive (+0.34), unlike the remaining members of the first transition series

(iiI) La(OH)₃ is more basic than Lu(OH)₃.

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Read Also:

• NCERT Solutions for Class 12 Chemistry Chapter 8 D and F Block Elements
• Chemistry Class 12 The d-and f-Block Elements Notes Chapter 8
• Class 12 Chemistry Chapter 8 The d & f Block Elements MCQs
• Important Questions for Class 12 Chemistry Chapter 8 – D and F Block Elements.