NCERT BOOK CLASS 12TH CHEMISTRY MCQ
Chapter 4 : The d- and f-Block Elements
Important MCQs with Answers
1. By what other name are d-block elements known?
a) Transition elements
b) Main group elements
c) Noble gases
d) Halogens
Answer: a) Transition elements
2. In d-block elements, electrons fill which subshell?
a) s
b) p
c) d
d) f
Answer: c) d
3. In which periods are d-block elements found?
a) 2 and 3
b) 3 to 5
c) 4 to 7
d) Only 7
Answer: c) 4 to 7
4. What is the most prominent characteristic of transition elements?
a) High electronegativity
b) Variable oxidation states
c) Low melting point
d) Inertness
Answer: b) Variable oxidation states
5. What is the electronic configuration of Copper (Cu)?
a) [Ar] 3d⁹ 4s²
b) [Ar] 3d¹⁰ 4s¹
c) [Ar] 3d⁸ 4s²
d) [Ar] 3d⁷ 4s²
Answer: b) [Ar] 3d¹⁰ 4s¹
6. What is the electronic configuration of Chromium (Cr)?
a) [Ar] 3d⁴ 4s²
b) [Ar] 3d⁵ 4s¹
c) [Ar] 3d⁶
d) [Ar] 3d³ 4s²
Answer: b) [Ar] 3d⁵ 4s¹
7. What is the reason for the colored compounds of transition metals?
a) d-d transition
b) High ionization energy
c) High electrical conductivity
d) High density
Answer: a) d-d transition
8. Which transition metal is liquid at room temperature?
a) Iron
b) Mercury
c) Copper
d) Zinc
Answer: b) Mercury
9. What is the consequence of lanthanide contraction?
a) Increase in the size of d-block elements
b) Similarity in the size of 4d and 5d series elements
c) Discovery of noble gases
d) Stability of p-block elements
Answer: b) Similarity in the size of 4d and 5d series elements
10. What is the oxidation state of Manganese (Mn) in KMnO₄?
a) +2
b) +4
c) +6
d) +7
Answer: d) +7
11. By what name are f-block elements known?
a) Inner transition elements
b) Main group elements
c) Non-metals
d) Noble gases
Answer: a) Inner transition elements
12. To which series do lanthanides belong?
a) 4f
b) 5f
c) 3d
d) 6p
Answer: a) 4f
13. To which series do actinides belong?
a) 4f
b) 5f
c) 6d
d) 7s
Answer: b) 5f
14. Which characteristic distinguishes lanthanides?
a) High conductivity
b) Similar properties
c) Radioactivity
d) High electronegativity
Answer: b) Similar properties
15. Uranium belongs to which group of elements?
a) Lanthanides
b) Actinides
c) Transition metals
d) Noble gases
Answer: b) Actinides
16. Why is the +3 oxidation state most common in lanthanides?
a) Stability of 4f electrons
b) High ionization energy
c) Low electronegativity
d) More metallic character
Answer: a) Stability of 4f electrons
17. Which of the following is not an actinide?
a) Thorium
b) Uranium
c) Plutonium
d) Tungsten
Answer: d) Tungsten
18. What causes lanthanide contraction?
a) Poor shielding of 4f electrons
b) High energy of 5d electrons
c) Decrease in nuclear charge
d) Influence of s-block elements
Answer: a) Poor shielding of 4f electrons
19. What is the most common oxidation state of Cerium (Ce)?
a) +2
b) +3
c) +4
d) +5
Answer: c) +4
20. Which lanthanide is radioactive?
a) Lanthanum
b) Promethium
c) Neodymium
d) Gadolinium
Answer: b) Promethium
21. What is the main reason for the high melting points of transition metals?
a) Incomplete d-subshell
b) Strong metallic bonding
c) Low density
d) High ionization energy
Answer: b) Strong metallic bonding
22. Which metal is used as a catalyst?
a) Na
b) Fe
c) Al
d) Mg
Answer: b) Fe
23. Which transition metal is used in thermometers?
a) Iron
b) Mercury
c) Copper
d) Zinc
Answer: b) Mercury
24. Nickel is primarily used in:
a) Stainless steel
b) Aluminum alloy
c) Brass
d) Bronze
Answer: a) Stainless steel
25. What is the color of Copper sulfate (CuSO₄)?
a) Red
b) Blue
c) Green
d) Yellow
Answer: b) Blue
26. What is the oxidation state of Chromium (Cr) in K₂Cr₂O₇?
a) +2
b) +4
c) +6
d) +7
Answer: c) +6
27. Which compound is colorless?
a) FeSO₄
b) CuSO₄
c) KMnO₄
d) ZnSO₄
Answer: d) ZnSO₄
28. What is the main purpose of making alloys?
a) To reduce the cost of metal
b) To improve the properties of metal
c) To make the metal lighter
d) To soften the metal
Answer: b) To improve the properties of metal
29. Which d-block element is essential for the human body?
a) Gold
b) Iron
c) Silver
d) Platinum
Answer: b) Iron
30. Which metal is used in electrical wires?
a) Sodium
b) Copper
c) Zinc
d) Nickel
Answer: b) Copper
31. Thorium is used in:
a) Glass industry
b) Nuclear reactors
c) Cement manufacturing
d) Fertilizers
Answer: b) Nuclear reactors
32. What is the main ore of Uranium?
a) Bauxite
b) Pitchblende
c) Hematite
d) Galena
Answer: b) Pitchblende
33. Lanthanides are used in:
a) TV screens
b) Fluorescent lamps
c) Carbon dating
d) Plastic manufacturing
Answer: b) Fluorescent lamps
34. Which actinide is used in atomic bombs?
a) Thorium
b) Plutonium
c) Uranium
d) Both b and c
Answer: d) Both b and c
35. Cerium is used in:
a) Alloy making
b) Glass polishing
c) As a catalyst
d) All of the above
Answer: d) All of the above
36. KMnO₄ is used as:
a) Reducing agent
b) Oxidizing agent
c) Neutralizing agent
d) Precipitating agent
Answer: b) Oxidizing agent
37. What is the color of Fe³⁺ ion?
a) Green
b) Yellow
c) Brown
d) Blue
Answer: c) Brown
38. What is CuSO₄·5H₂O called?
a) Gypsum
b) Blue vitriol
c) Caustic soda
d) Saltpetre
Answer: b) Blue vitriol
39. Which compound is magnetic?
a) FeCl₂
b) ZnCl₂
c) CuCl₂
d) NaCl
Answer: a) FeCl₂
40. In AgNO₃ + NaCl → AgCl + NaNO₃, what is the color of AgCl precipitate?
a) Black
b) White
c) Yellow
d) Green
Answer: b) White
41. Potassium dichromate (K₂Cr₂O₇) is mainly used in:
a) Food preservative
b) Leather industry
c) Pharmaceuticals
d) Plastic industry
Answer: b) Leather industry
42. What is the color of an aqueous solution of copper sulfate (CuSO₄)?
a) Colorless
b) Blue
c) Green
d) Yellow
Answer: b) Blue
43. Which of the following compounds is colored?
a) ZnSO₄
b) FeSO₄·7H₂O (Green)
c) MgSO₄·7H₂O
d) Na₂SO₄
Answer: b) FeSO₄·7H₂O
44. What is the common name for Mercuric chloride (HgCl₂)?
a) Calomel
b) Corrosive sublimate
c) Verdigris
d) Mohr’s salt
Answer: b) Corrosive sublimate
45. Which compound is used in water purification?
a) KMnO₄
b) K₂Cr₂O₇
c) CuSO₄
d) FeSO₄
Answer: a) KMnO₄
46. Why is the +3 oxidation state most stable in lanthanides?
a) Complete filling of 4f subshell
b) Empty 5d subshell
c) Poor shielding of 4f electrons
d) High ionization enthalpy
Answer: c) Poor shielding of 4f electrons
47. Most actinide compounds are:
a) Colorless
b) Colored
c) Highly conductive
d) Low melting
Answer: b) Colored
48. Which actinide is most abundant in nature?
a) Thorium (Th)
b) Uranium (U)
c) Plutonium (Pu)
d) Neptunium (Np)
Answer: b) Uranium
49. Which method is used for the extraction of lanthanides?
a) Electrolysis
b) Solvent extraction
c) Steam distillation
d) Sublimation
Answer: b) Solvent extraction
50. The alloy “Misch metal” mainly consists of:
a) Lanthanides (~95%) + Iron (~5%)
b) Actinides (~95%) + Carbon (~5%)
c) Alkali metals (~95%) + Aluminum (~5%)
d) Transition metals (~95%) + Silicon (~5%)
Answer: a) Lanthanides (~95%) + Iron (~5%)
51. Which transition metal is used as a catalyst in hydrogenation reactions?
a) Platinum (Pt)
b) Zinc (Zn)
c) Copper (Cu)
d) Silver (Ag)
Answer: a) Platinum
52. Which transition metal ion is colorless?
a) Fe³⁺
b) Cu²⁺
c) Zn²⁺
d) Cr³⁺
Answer: c) Zn²⁺
53. Which transition metal is not used in currency coins?
a) Nickel (Ni)
b) Copper (Cu)
c) Sodium (Na)
d) Silver (Ag)
Answer: c) Sodium
54. In electrolytic refining, the impure metal is made the:
a) Cathode
b) Anode
c) Electrolyte
d) Diaphragm
Answer: b) Anode
55. Which compound exhibits magnetic properties?
a) TiO₂
b) Fe₃O₄
c) ZnO
d) CuCl₂
Answer: b) Fe₃O₄
56. Which oxidation state in lanthanides is considered “anomalous”?
a) +2
b) +3
c) +4
d) +5
Answer: c) +4
57. Which actinide is not found in nature?
a) Uranium (U)
b) Thorium (Th)
c) Plutonium (Pu)
d) Neptunium (Np)
Answer: d) Neptunium
58. In lanthanide extraction, the ion-exchange method works based on:
a) Density
b) Ionic size
c) Magnetic properties
d) Volatility
Answer: b) Ionic size
59. What is the color of Cerium dioxide (CeO₂)?
a) White
b) Yellow
c) Green
d) Black
Answer: a) White
60. Which lanthanide reacts with water?
a) Lanthanum (La)
b) Ytterbium (Yb)
c) Lutetium (Lu)
d) None
Answer: a) Lanthanum
61. Zinc (Zn) is mainly used in:
a) Electrical wires
b) Galvanization
c) Glass manufacturing
d) Fertilizers
Answer: b) Galvanization
62. Which alloy is made of nickel and copper?
a) Brass
b) Bronze
c) Monel metal
d) Steel
Answer: c) Monel metal
63. Vanadium pentoxide (V₂O₅) is used in:
a) Plastic industry
b) Contact process (as a catalyst)
c) Glass manufacturing
d) Paper industry
Answer: b) Contact process
64. Which transition metal oxide acts as a catalyst in ammonia oxidation?
a) Cr₂O₃
b) PtO₂
c) Fe₂O₃
d) MnO₂
Answer: b) PtO₂
65. What is the chromium content in stainless steel?
a) 5-10%
b) 10-20%
c) 20-30%
d) 30-40%
Answer: b) 10-20%
66. In K₂Cr₂O₇ + H₂SO₄ + H₂O₂ → Product, what is the oxidation state of chromium?
a) +3
b) +6
c) +2
d) +5
Answer: a) +3
67. In Fe³⁺ + SCN⁻ → Product, what color is observed?
a) Blue
b) Green
c) Red
d) Yellow
Answer: c) Red
68. In CuSO₄ + NH₄OH (excess) → Product, what is the color of the copper complex?
a) Blue
b) Deep blue
c) Green
d) Colorless
Answer: b) Deep blue
69. In MnO₄⁻ + H⁺ + Fe²⁺ → Product, what is the change in Mn’s oxidation state?
a) +7 to +2
b) +6 to +3
c) +4 to +2
d) +5 to +1
Answer: a) +7 to +2
70. In AgNO₃ + NaCl → AgCl + NaNO₃, what is the color of the AgCl precipitate?
a) Black
b) White
c) Yellow
d) Green
Answer: b) White
71. Which transition metal is used as a neutron absorber in nuclear reactors?
a) Zirconium (Zr)
b) Cadmium (Cd)
c) Tungsten (W)
d) Molybdenum (Mo)
Answer: b) Cadmium
72. Which transition metal oxide is amphoteric?
a) Cr₂O₃
b) Fe₂O₃
c) CuO
d) ZnO
Answer: d) ZnO
73. Chalcopyrite (CuFeS₂) is the ore of:
a) Copper
b) Iron
c) Gold
d) Silver
Answer: a) Copper
74. Which compound is known as “Red Blood”?
a) K₃[Fe(CN)₆]
b) K₄[Fe(CN)₆]
c) Fe(SCN)₃
d) Fe₂O₃
Answer: a) K₃[Fe(CN)₆]
75. Which transition metal compound is known as “Mohr’s salt”?
a) FeSO₄·(NH₄)₂SO₄·6H₂O
b) CuSO₄·5H₂O
c) K₂Cr₂O₇
d) KMnO₄
Answer: a) FeSO₄·(NH₄)₂SO₄·6H₂O