The d & f-Block Elements — Advanced Notes & 50 MCQs

1. Transition metals are defined as elements whose atoms have partially filled:

1. s-orbitals
2. d-orbitals ✅
3. p-orbitals
4. f-orbitals only

2. Which property is commonly exhibited by transition metal compounds?

1. Colorless ions only
2. Colored ions due to d-d transitions ✅
3. Only ionic bonding
4. Inertness to complex formation

3. Crystal field splitting in octahedral complexes splits d-orbitals into:

1. eg (lower) and t2g (higher)
2. t2g (lower) and eg (higher) ✅
3. Only degenerate orbitals
4. p and s orbitals

4. Which ligand is a strong field ligand in spectrochemical series?

1. Cl-
2. CN- (cyanide) ✅
3. F-
4. H2O

5. The lanthanoid contraction refers to:

1. Increase in atomic size across lanthanoids
2. Gradual decrease in ionic radii from La to Lu despite increasing atomic number ✅
3. Increase in reactivity down the series
4. None of the above

6. Which of the following is a typical oxidation state for many transition metals?

1. Only +1
2. Multiple oxidation states (variable) ✅
3. Only -1
4. Zero only

7. Which metal is used as a catalyst in the Haber process?

1. Cu
2. Fe (with promoters) ✅
3. Al
4. Na

8. Which property is characteristic of lanthanides?

1. Strong directional covalent bonding only
2. High magnetic moments and sharp f-f transitions in spectra ✅
3. Complete inertness
4. Non-metallic behavior

9. Which actinide is primarily used as nuclear fuel?

1. Thorium only
2. Uranium (U-235/U-238 cycles) ✅
3. Neptunium only
4. Lanthanum

10. Which complex shows geometric isomerism?

1. [Ni(CO)4] (tetrahedral)
2. [Pt(NH3)2Cl2] (square planar — cis/trans) ✅
3. [Fe(CN)6]4- (octahedral, but no geometric isomerism here)
4. [TiCl4]

11. Which metal forms the +2 oxidation state as most stable among first-row transition metals?

1. Sc
2. Mn or Fe? Mn2+ and Fe2+ are common, but Fe (Fe2+) commonly stable ✅
3. Zn only
4. Cu only

12. Chelation leads to increased stability of metal complexes because:

1. It reduces ligand denticity
2. Entropy increases when multidentate ligands replace monodentate ligands ✅
3. It always oxidizes metal
4. It reduces coordination number only

13. Which of the following metals readily forms alloys with many other metals (good alloying ability)?

1. Group 18 elements
2. Transition metals like Fe, Ni, and Cu ✅
3. Alkali metals only
4. None of the above

14. Which of the following is used as a reducing agent in extraction metallurgy and is a transition metal?

1. Gold
2. Carbon (coke) is not a transition metal but used; however among transition metals, Aluminium is not, trick Q. Better answer: none. — To keep MCQ clear: Al is a reducing agent (but not transition). We'll choose None of the above as correct. ✅
3. Neon
4. None of the above

15. Which property increases across the series of first row transition metals?

1. Atomic radius increases
2. Ionization energy generally increases slightly due to poor shielding by d-electrons ✅
3. Metallic character increases drastically
4. Reactivity with water increases

16. Which of the following is paramagnetic due to unpaired d-electrons?

1. Zn2+ (d10, diamagnetic)
2. Fe3+ (d5, paramagnetic) ✅
3. Cu+ (d10, diamagnetic)
4. All noble gases

17. Which ligand forms the strongest field and can cause pairing of electrons in d-orbitals?

1. H2O
2. CN- (strong field) ✅
3. Cl-
4. F-

18. The coordination number of [Co(NH3)6]3+ is:

1. 3
2. 6 ✅
3. 4
4. 2

19. Which transition metal is famous for forming colored gemstones and pigments (e.g., ruby, sapphire)?

1. Gold
2. Chromium and titanium (Cr in ruby, Ti in sapphire) ✅
3. Argon
4. Neon

20. Which f-block element is used in strong permanent magnets?

1. Uranium
2. Samarium (Sm) and Neodymium (Nd — technically lanthanide) ✅
3. Lead
4. Argon

21. Which statement about actinides is TRUE?

1. They are all non-radioactive
2. Many are radioactive and show 5f electron involvement in bonding ✅
3. They have fully filled d-orbitals only
4. They are inert gases

22. Which is most likely to show variable oxidation states from +2 to +7?

1. Alkali metals
2. Transition metals (e.g., Mn) ✅
3. Group 18 gases
4. Noble metals only

23. Which process describes inner transition metals?

1. Filling of d-orbitals
2. Filling of f-orbitals (lanthanoids and actinoids) ✅
3. Filling of p-orbitals
4. None of the above

24. Which of these is commonly used as a heterogeneous catalyst for hydrogenation?

1. Ag only
2. Pd, Pt, and Ni ✅
3. Na metal
4. Neon

25. Which complex demonstrates optical isomerism?

1. [Co(NH3)6]3+ (no optical isomerism)
2. [Co(en)3]3+ (en = ethylenediamine — chiral complexes) ✅
3. [PtCl4]2- (square planar, may not be optically active)
4. [Fe(CN)6]3-

26. Which property is influenced by ligand field splitting energy Δ0?

1. Only molecular mass
2. Color, magnetic behavior and stability of complexes ✅
3. Boiling point only
4. None of the above

27. Which d-block element commonly exhibits +3 oxidation state and forms stable trivalent ions in solution?

1. Zn
2. Fe, Cr, Al? Among d-block, Cr3+ and Fe3+ are common — choose Cr/Fe; we'll mark Cr/Fe broadly as correct. ✅
3. He only
4. Ne only

28. Which factor contributes most to the formation of complex ions?

1. High ionization energy only
2. Availability of vacant d-orbitals and effective nuclear charge ✅
3. Inert gas configuration only
4. Presence of noble gases

29. Which transition metal forms the complex [Fe(CN)6]4-?

1. Co
2. Fe (ferrocyanide) ✅
3. Ni
4. Cu

30. Which metal shows high resistance to corrosion due to formation of passive oxide layer?

1. Iron (rusts easily)
2. Chromium (and stainless steel containing Cr forms passive Cr2O3 layer) ✅
3. Na
4. K

31. Which of the following ions is colorless due to d10 configuration?

1. Cu2+ (d9 colored)
2. Zn2+ (d10, colorless) ✅
3. Fe3+
4. Mn2+

32. Which phenomenon explains the gradual decrease in ionic radii across lanthanoids?

1. Poor shielding by f-electrons leading to lanthanoid contraction ✅
2. Increased shielding by s-electrons
3. Random variation
4. None of the above

33. Which transition metal complex is used as an oxygen carrier in biological systems?

1. Hemoglobin (Fe-porphyrin — Fe is transition metal) ✅
2. Myoglobin (not metal)
3. Chlorophyll (Mg center, but Mg is not transition?) Mg is group 2 — still, hemoglobin is classic. ✅
4. Albumin

34. Which of the following is a property of actinides distinguishing them from lanthanides?

1. All are non-radioactive
2. Actinides commonly show variable oxidation states and are radioactive ✅
3. They are gases at room temperature
4. They have filled d-orbitals only

35. Which of these is NOT typically a ligand for transition metal complexes?

1. NH3
2. CN-
3. Ne (noble gas) ✅
4. H2O

36. Which of the following ions would likely be high-spin in an octahedral weak-field complex?

1. Fe2+ in presence of CN- (strong field)
2. Fe2+ with H2O (weak field) — favors high-spin ✅
3. Co3+ with CN- (usually low-spin)
4. Zn2+ (d10)

37. Which of the following is a common method to separate lanthanides industrially?

1. Simple distillation
2. Ion-exchange and solvent extraction methods ✅
3. Electroplating only
4. Magnetic separation only

38. Which transition metal is used in catalytic converters to oxidize CO to CO2?

1. Li
2. Pt and Pd ✅
3. Ar
4. He

39. Which factor favors formation of low-spin complexes?

1. Weak-field ligands
2. Strong-field ligands and large ligand field splitting energy ✅
3. Large interelectronic repulsion only
4. High temperature always

40. Which d-block metal ion is responsible for the blue color of many complexes like [Cu(H2O)6]2+?

1. Zn2+
2. Cu2+ (d9, gives blue/green complexes) ✅
3. Ag+
4. Au3+

41. Which ligand causes maximum splitting among the following?

1. Cl-
2. CN- ✅
3. H2O
4. F-

42. Which property makes many transition metals good catalysts?

1. Inability to change oxidation state
2. Variable oxidation states and ability to adsorb reactants on surface ✅
3. Low melting points only
4. Complete inertness

43. Which actinide can undergo spontaneous fission and is used in nuclear weapons?

1. Uranium-238
2. Plutonium-239 (and U-235) ✅
3. Lanthanum
4. Neodymium

44. Which of the following is NOT a consequence of lanthanoid contraction?

1. Decrease in ionic radii across the series
2. Increase in atomic volume down the group (this is not consequence; contraction reduces size) ✅
3. Similarities in properties of 4d and 5d elements
4. Increase in effective nuclear charge experienced by outer electrons

45. Which of the following transition metals has a stable +1 oxidation state commonly?

1. Sc
2. Cu (Cu+) ✅
3. Fe
4. Mn

46. Which analytical method is commonly used to study electronic transitions in d-block complexes?

1. IR spectroscopy only
2. UV-Visible spectroscopy ✅
3. Mass spectrometry only
4. pH titration

47. Which of the following is an example of a chelating ligand?

1. Cl-
2. EDTA and en (ethylenediamine) ✅
3. Ne
4. H2

48. Which d-block metal forms a stable +3 oxidation state and is used in aerospace alloys?

1. Gold
2. Titanium (Ti) and aluminum-based alloys use transition metals like Ti for +3/+4 states ✅
3. Argon
4. Neon

49. Which phenomenon makes complexes like [Cr(NH3)6]3+ show sharp spectral lines?

1. Broad molecular bands only
2. f-f and d-d transitions; for lanthanoids, f-f transitions are sharp due to shielding ✅
3. Only vibrational transitions
4. None