MCQs on d- and f-Block Elements – Class 12 Chemistry
MCQs on d- and f-Block Elements – Class 12 Chemistry
Inorganic Chemistry | NCERT-Based | MCQs with Answers & Explanations
The following 50 Multiple Choice Questions (MCQs) are strictly prepared as per the NCERT syllabus for CBSE Class 12 Chemistry.
Questions are arranged section-wise (d-Block Elements and f-Block Elements) and each MCQ is supported by a clear, exam-oriented explanation, making this set ideal for CBSE board exam preparation.
Section A: General Properties of d-Block Elements
Q1. d-Block elements are also known as:
A. Inner transition elements
B. Representative elements
C. Transition elements
D. Noble metals
Answer: C
Explanation:
d-Block elements have partially filled d-orbitals in their ground or common oxidation states and are therefore called transition elements.
Q2. Which property is characteristic of transition elements?
A. Low melting points
B. Formation of colored compounds
C. High electronegativity
D. Non-metallic nature
Answer: B
Explanation:
Partially filled d-orbitals allow d–d electronic transitions, resulting in colored compounds.
Q3. Which transition metal shows the maximum number of oxidation states?
A. Iron
B. Chromium
C. Manganese
D. Copper
Answer: C
Explanation:
Manganese exhibits oxidation states from +2 to +7 due to availability of multiple valence electrons.
Q4. Which of the following is not a transition metal?
A. Sc
B. Zn
C. Fe
D. Cu
Answer: B
Explanation:
Zinc has a completely filled d¹⁰ configuration in both atom and ions, so it is not considered a transition element.
Q5. The ability of transition metals to form complexes is due to:
A. High atomic size
B. High ionization energy
C. Availability of vacant d-orbitals
D. Low density
Answer: C
Explanation:
Vacant d-orbitals allow transition metals to accept lone pairs from ligands and form complex compounds.
Section B: Electronic Configuration & Oxidation States
Q6. The general electronic configuration of d-block elements is:
A. ns² np⁶
B. ns² (n–1)d¹–¹⁰
C. ns¹ np¹
D. ns² nd¹⁰
Answer: B
Explanation:
d-Block elements have electrons filling the (n–1)d orbitals along with ns orbitals.
Q7. Why do transition metals show variable oxidation states?
A. Due to high atomic mass
B. Due to similar energies of ns and (n–1)d orbitals
C. Due to low electronegativity
D. Due to metallic bonding
Answer: B
Explanation:
Both ns and (n–1)d electrons can participate in bonding, resulting in variable oxidation states.
Q8. The most common oxidation state of iron is:
A. +1
B. +2
C. +3
D. +4
Answer: C
Explanation:
Iron commonly exists in +2 and +3 states, with +3 being more stable.
Q9. Which oxidation state is most stable for copper?
A. +1
B. +2
C. +3
D. 0
Answer: B
Explanation:
Cu²⁺ has a stable electronic configuration and strong hydration energy.
Q10. The highest oxidation state shown by transition metals corresponds to:
A. Group number
B. Atomic number
C. Atomic size
D. Melting point
Answer: A
Explanation:
The maximum oxidation state of transition metals often equals their group number.
Section C: Magnetic & Catalytic Properties
Q11. Paramagnetism in transition metals is due to:
A. Paired electrons
B. Unpaired electrons
C. High density
D. Metallic bonding
Answer: B
Explanation:
Presence of unpaired d-electrons causes paramagnetic behavior.
Q12. Which ion is diamagnetic?
A. Fe²⁺
B. Mn²⁺
C. Zn²⁺
D. Cu²⁺
Answer: C
Explanation:
Zn²⁺ has a d¹⁰ configuration with all electrons paired.
Q13. Which transition metal is used as a catalyst in the Haber process?
A. Copper
B. Iron
C. Nickel
D. Platinum
Answer: B
Explanation:
Iron provides a large surface area and suitable adsorption sites for nitrogen and hydrogen.
Q14. Which metal is commonly used as a catalyst in hydrogenation reactions?
A. Chromium
B. Nickel
C. Iron
D. Zinc
Answer: B
Explanation:
Nickel efficiently adsorbs hydrogen and organic molecules during hydrogenation.
Q15. The catalytic activity of transition metals is due to:
A. High atomic mass
B. Variable oxidation states and surface adsorption
C. High density
D. Metallic character
Answer: B
Explanation:
Transition metals form intermediate complexes and facilitate redox reactions.
Section D: Alloy Formation & Physical Properties
Q16. Transition metals form alloys because:
A. They are non-metals
B. Their atomic sizes are similar
C. They have high electronegativity
D. They are radioactive
Answer: B
Explanation:
Similar atomic sizes allow easy substitution in the crystal lattice.
Q17. Brass is an alloy of:
A. Copper and tin
B. Copper and zinc
C. Iron and carbon
D. Nickel and chromium
Answer: B
Explanation:
Brass is a Cu–Zn alloy used widely due to corrosion resistance.
Q18. Which transition metal has the highest melting point?
A. Iron
B. Tungsten
C. Copper
D. Chromium
Answer: B
Explanation:
Tungsten has very strong metallic bonding, giving it the highest melting point.
Q19. Which metal is used for electroplating iron to prevent corrosion?
A. Copper
B. Zinc
C. Chromium
D. Nickel
Answer: C
Explanation:
Chromium provides a protective, corrosion-resistant coating.
Q20. Which transition metal is essential for oxygen transport in blood?
A. Copper
B. Zinc
C. Iron
D. Cobalt
Answer: C
Explanation:
Iron is present in haemoglobin, enabling oxygen transport.
Section E: f-Block Elements – Lanthanoids
Q21. f-Block elements are also called:
A. Transition elements
B. Inner transition elements
C. Noble elements
D. Representative elements
Answer: B
Explanation:
f-Block elements involve filling of inner f-orbitals, hence called inner transition elements.
Q22. Lanthanoids belong to atomic numbers:
A. 57–71
B. 58–72
C. 56–70
D. 59–73
Answer: A
Explanation:
Lanthanoids extend from Lanthanum (57) to Lutetium (71).
Q23. The common oxidation state of lanthanoids is:
A. +2
B. +3
C. +4
D. +1
Answer: B
Explanation:
Loss of two 6s and one 5d electron gives a stable +3 oxidation state.
Q24. Lanthanoid contraction is due to:
A. Poor shielding by 4f electrons
B. High electronegativity
C. Nuclear instability
D. Large atomic size
Answer: A
Explanation:
4f electrons shield nuclear charge poorly, causing gradual decrease in atomic size.
Q25. Which element shows maximum paramagnetism among lanthanoids?
A. La
B. Ce
C. Gd
D. Lu
Answer: C
Explanation:
Gadolinium has 7 unpaired electrons, giving maximum paramagnetism.
Section F: Actinoids
Q26. Actinoids belong to atomic numbers:
A. 57–71
B. 72–86
C. 89–103
D. 90–104
Answer: C
Explanation:
Actinoids range from Actinium (89) to Lawrencium (103).
Q27. Most actinoids are:
A. Non-metals
B. Noble gases
C. Radioactive
D. Metalloids
Answer: C
Explanation:
Actinoids are radioactive due to unstable nuclei.
Q28. Which actinoid is used as nuclear fuel?
A. Thorium
B. Uranium
C. Neptunium
D. Plutonium
Answer: B
Explanation:
Uranium-235 undergoes nuclear fission, releasing large energy.
Q29. Actinoids show a greater number of oxidation states than lanthanoids because:
A. Larger atomic size
B. Participation of 5f, 6d, and 7s electrons
C. High electronegativity
D. High density
Answer: B
Explanation:
Comparable energies of multiple orbitals allow variable oxidation states.
Q30. Which actinoid is used in smoke detectors?
A. Uranium
B. Thorium
C. Americium
D. Curium
Answer: C
Explanation:
Americium-241 is used due to its alpha-emitting property.
Section G: NCERT-Based Mixed MCQs
Q31. Which ion gives a blue color in aqueous solution?
A. Fe³⁺
B. Cu²⁺
C. Ni²⁺
D. Zn²⁺
Answer: B
Explanation:
Cu²⁺ ions show a blue color due to d–d transitions.
Q32. Which metal is used in making stainless steel?
A. Zinc
B. Chromium
C. Copper
D. Silver
Answer: B
Explanation:
Chromium improves corrosion resistance in stainless steel.
Q33. Which transition metal compound is black in color?
A. KMnO₄
B. MnO₂
C. FeCl₃
D. CuSO₄
Answer: B
Explanation:
MnO₂ is a black solid used as an oxidizing agent.
Q34. The oxidation state of manganese in KMnO₄ is:
A. +5
B. +6
C. +7
D. +4
Answer: C
Explanation:
Potassium permanganate contains Mn in its highest oxidation state (+7).
Q35. Which transition metal is liquid near room temperature?
A. Mercury
B. Gallium
C. Cesium
D. Bromine
Answer: B
Explanation:
Gallium melts at about 30°C, slightly above room temperature.
Q36. Which compound is used as a mordant in dyeing?
A. FeSO₄
B. Al₂(SO₄)₃
C. CuSO₄
D. ZnCl₂
Answer: B
Explanation:
Aluminium salts help fix dyes onto fabrics.
Q37. Which metal shows maximum hardness?
A. Iron
B. Chromium
C. Copper
D. Zinc
Answer: B
Explanation:
Chromium is extremely hard due to strong metallic bonding.
Q38. Which ion has the highest magnetic moment?
A. Fe²⁺
B. Mn²⁺
C. Co²⁺
D. Ni²⁺
Answer: B
Explanation:
Mn²⁺ has five unpaired electrons, giving maximum magnetic moment.
Q39. Which metal is used in making coins?
A. Silver
B. Copper
C. Nickel
D. All of these
Answer: D
Explanation:
Coins are made from Cu, Ni, and Ag alloys for durability.
Q40. Which metal is essential for chlorophyll formation?
A. Iron
B. Magnesium
C. Zinc
D. Copper
Answer: A
Explanation:
Iron plays a crucial role in chlorophyll synthesis.
Q41. The color of KMnO₄ solution is due to:
A. Charge transfer
B. d–d transition
C. Atomic excitation
D. Hybridisation
Answer: A
Explanation:
The intense purple color arises from charge-transfer transitions.
Q42. Which metal is used in making electric wires due to high conductivity?
A. Iron
B. Copper
C. Zinc
D. Aluminium
Answer: B
Explanation:
Copper has excellent electrical conductivity.
Q43. Which element is used in making thermocouples?
A. Iron
B. Nickel
C. Copper
D. Zinc
Answer: B
Explanation:
Nickel alloys are used due to thermal stability.
Q44. Which transition metal has a completely filled d-orbital in +2 state?
A. Fe
B. Cu
C. Zn
D. Co
Answer: C
Explanation:
Zn²⁺ has a d¹⁰ configuration, making it diamagnetic.
Q45. Which compound is used in photography?
A. AgCl
B. CuSO₄
C. FeCl₃
D. ZnS
Answer: A
Explanation:
Silver halides are photosensitive.
Q46. The contraction in actinoids is greater than lanthanoids due to:
A. Higher nuclear charge
B. Poor shielding by 5f electrons
C. Larger atomic size
D. Radioactivity
Answer: B
Explanation:
5f electrons shield poorly, causing actinoid contraction.
Q47. Which metal is used in jet engines?
A. Aluminium
B. Titanium
C. Iron
D. Copper
Answer: B
Explanation:
Titanium has high strength-to-weight ratio and corrosion resistance.
Q48. Which ion shows no color in aqueous solution?
A. Cu²⁺
B. Fe³⁺
C. Zn²⁺
D. Co²⁺
Answer: C
Explanation:
Zn²⁺ has no unpaired electrons, so no d–d transitions occur.
Q49. Which metal is used for galvanization?
A. Iron
B. Copper
C. Zinc
D. Aluminium
Answer: C
Explanation:
Zinc coating prevents corrosion of iron.
Q50. Which f-block element is used as a catalyst in petroleum cracking?
A. Cerium
B. Lanthanum
C. Neodymium
D. Europium
Answer: A
Explanation:
Cerium oxide is used in catalytic converters and cracking reactions.
✅ Exam Tip:
These MCQs are fully NCERT-aligned, concept-driven, and ideal for CBSE board exams, revision tests, and assertion–reason practice.