The d- and f-Block Elements Practice

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NEET Chemistry - Chapter 27

The d- and f-Block Elements Practice Tests

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Definition
1. Transition elements generally have partially filled:
- A. d-orbitals in atom or common ion (Correct)
- B. p-orbitals only
- C. f-orbitals only
- D. s-orbitals only
Explanation: That is the accepted defining feature.
Series
2. The first transition series runs from:
- A. Sc to Zn (Correct)
- B. K to Kr
- C. La to Lu
- D. Ac to Lr
Explanation: These are the 3d elements.
Color
3. Many transition-metal compounds are colored because of:
- A. d-d electronic transitions (Correct)
- B. hydrogen bonding only
- C. complete octet
- D. lack of unpaired electrons
Explanation: Partially filled d-orbitals allow such transitions.
Oxidation state
4. Variable oxidation state in transition elements is due to similar energies of:
- A. ns and (n-1)d electrons (Correct)
- B. 1s and 2p electrons
- C. f and g orbitals
- D. only p electrons
Explanation: Both sets may participate in bonding.
Catalysis
5. Transition metals often act as good catalysts because they show:
- A. variable oxidation state and adsorption ability (Correct)
- B. only low density
- C. only high electronegativity
- D. always +1 state
Explanation: Surface behavior and redox flexibility help catalysis.
Magnetism
6. Paramagnetism in transition-metal ions is due to:
- A. unpaired electrons (Correct)
- B. paired electrons only
- C. empty shells only
- D. hydrogen bonding
Explanation: Magnetic moment depends on the count of unpaired electrons.
Scandium
7. Among Sc, Ti, V, Cr, Mn, the highest oxidation state is shown by:
- A. Mn (Correct)
- B. Sc
- C. Ti
- D. Cr only
Explanation: Mn reaches +7 in permanganate.
Chromium
8. Electronic configuration of chromium is exceptional because it is:
- A. [Ar] 3d$^5$ 4s$^1$ (Correct)
- B. [Ar] 3d$^4$ 4s$^2$
- C. [Ar] 3d$^6$ 4s$^0$
- D. [Ar] 3d$^3$ 4s$^3$
Explanation: Half-filled d-subshell stability causes the exception.
Copper
9. Electronic configuration of copper is:
- A. [Ar] 3d$^{10}$ 4s$^1$ (Correct)
- B. [Ar] 3d$^9$ 4s$^2$
- C. [Ar] 3d$^8$ 4s$^3$
- D. [Ar] 3d$^{10}$ 4s$^2$
Explanation: Filled d-subshell gives extra stability.
Ion color
10. Zn$^{2+}$ compounds are generally colorless because Zn$^{2+}$ has:
- A. completely filled d-subshell (Correct)
- B. empty p-subshell
- C. high hydration only
- D. no nucleus
Explanation: No d-d transitions are possible.
Lanthanoids
11. The progressive decrease in size across lanthanoids is called:
- A. lanthanoid contraction (Correct)
- B. inert pair effect
- C. diagonal relationship
- D. back bonding
Explanation: Poor shielding by 4f electrons causes it.
Lanthanoid contraction
12. A major consequence of lanthanoid contraction is similarity between:
- A. Zr and Hf (Correct)
- B. Na and K
- C. Fe and Cu
- D. Li and Be
Explanation: Their radii become very similar.
Actinoids
13. Actinoids show a wider range of oxidation states mainly because:
- A. 5f, 6d, and 7s energies are comparable (Correct)
- B. they are all colorless
- C. they have no unpaired electrons
- D. they are noble gases
Explanation: More orbitals can participate in bonding.
KMnO4
14. Potassium permanganate is a strong:
- A. oxidizing agent (Correct)
- B. reducing agent only
- C. acid only
- D. polymer
Explanation: Mn in +7 state is easily reduced.
K2Cr2O7
15. Potassium dichromate is orange because chromium is in oxidation state:
- A. +6 (Correct)
- B. +3
- C. +2
- D. +7
Explanation: Dichromate contains Cr(VI).
Interstitial compounds
16. Transition metals form interstitial compounds because:
- A. small atoms occupy gaps in metal lattice (Correct)
- B. they are non-metals
- C. they lack metallic bonding
- D. they contain only s electrons
Explanation: H, C, and N can fit into interstitial sites.
Alloy
17. An alloy is a homogeneous mixture of:
- A. metals or metal with non-metal (Correct)
- B. only gases
- C. only salts
- D. only organic compounds
Explanation: Alloys modify physical properties.
Hardness
18. Transition metals generally have high enthalpy of atomization due to:
- A. strong metallic bonding from many unpaired electrons (Correct)
- B. hydrogen bonds
- C. low nuclear charge
- D. absence of d electrons
Explanation: This contributes to hardness and high melting points.
Magnetic moment
19. The spin-only magnetic moment is primarily determined by:
- A. number of unpaired electrons (Correct)
- B. number of neutrons
- C. oxidation state only
- D. mass number
Explanation: More unpaired electrons give larger moment.
Complex formation
20. Transition metals readily form complexes because they have:
- A. small size, high charge, and vacant orbitals (Correct)
- B. only large size
- C. no valence electrons
- D. low melting points
Explanation: They accept electron pairs from ligands.
d-block logic
21. The cleanest route through this chapter is to organize facts by configuration exceptions, oxidation states, color, magnetism, and:
- A. lanthanoid contraction (Correct)
- B. hybridization of methane
- C. osmotic pressure
- D. soap micelles
Explanation: That captures most repeated NEET asks.
Overall
22. The top-scoring direct questions in this chapter are electronic configurations, oxidizing agents, and:
- A. color/magnetism logic (Correct)
- B. surface adsorption
- C. gas diffusion
- D. unit-cell defects
Explanation: These are repeatedly tested.
Catalyst example
23. V$_2$O$_5$ is used as catalyst in:
- A. contact process (Correct)
- B. Haber process only
- C. Bayer process
- D. soap formation
Explanation: It catalyzes oxidation of SO$_2$ to SO$_3$.
Ferromagnetism
24. Among common first-row ions, the one with maximum unpaired electrons is often:
- A. Mn$^{2+}$ (Correct)
- B. Zn$^{2+}$
- C. Cu$^+$
- D. Sc$^{3+}$
Explanation: It has a 3d$^5$ configuration with five unpaired electrons.
Lanthanoids use
25. Cerium is a lanthanoid element of the:
- A. f-block (Correct)
- B. s-block
- C. p-block
- D. noble-gas group
Explanation: Lanthanoids occupy the f-block.
Definition
26. Transition elements generally have partially filled:
- A. d-orbitals in atom or common ion (Correct)
- B. p-orbitals only
- C. f-orbitals only
- D. s-orbitals only
Explanation: That is the accepted defining feature.
Series
27. The first transition series runs from:
- A. Sc to Zn (Correct)
- B. K to Kr
- C. La to Lu
- D. Ac to Lr
Explanation: These are the 3d elements.
Color
28. Many transition-metal compounds are colored because of:
- A. d-d electronic transitions (Correct)
- B. hydrogen bonding only
- C. complete octet
- D. lack of unpaired electrons
Explanation: Partially filled d-orbitals allow such transitions.
Oxidation state
29. Variable oxidation state in transition elements is due to similar energies of:
- A. ns and (n-1)d electrons (Correct)
- B. 1s and 2p electrons
- C. f and g orbitals
- D. only p electrons
Explanation: Both sets may participate in bonding.
Catalysis
30. Transition metals often act as good catalysts because they show:
- A. variable oxidation state and adsorption ability (Correct)
- B. only low density
- C. only high electronegativity
- D. always +1 state
Explanation: Surface behavior and redox flexibility help catalysis.
Magnetism
31. Paramagnetism in transition-metal ions is due to:
- A. unpaired electrons (Correct)
- B. paired electrons only
- C. empty shells only
- D. hydrogen bonding
Explanation: Magnetic moment depends on the count of unpaired electrons.
Scandium
32. Among Sc, Ti, V, Cr, Mn, the highest oxidation state is shown by:
- A. Mn (Correct)
- B. Sc
- C. Ti
- D. Cr only
Explanation: Mn reaches +7 in permanganate.
Chromium
33. Electronic configuration of chromium is exceptional because it is:
- A. [Ar] 3d$^5$ 4s$^1$ (Correct)
- B. [Ar] 3d$^4$ 4s$^2$
- C. [Ar] 3d$^6$ 4s$^0$
- D. [Ar] 3d$^3$ 4s$^3$
Explanation: Half-filled d-subshell stability causes the exception.
Copper
34. Electronic configuration of copper is:
- A. [Ar] 3d$^{10}$ 4s$^1$ (Correct)
- B. [Ar] 3d$^9$ 4s$^2$
- C. [Ar] 3d$^8$ 4s$^3$
- D. [Ar] 3d$^{10}$ 4s$^2$
Explanation: Filled d-subshell gives extra stability.
Ion color
35. Zn$^{2+}$ compounds are generally colorless because Zn$^{2+}$ has:
- A. completely filled d-subshell (Correct)
- B. empty p-subshell
- C. high hydration only
- D. no nucleus
Explanation: No d-d transitions are possible.
Lanthanoids
36. The progressive decrease in size across lanthanoids is called:
- A. lanthanoid contraction (Correct)
- B. inert pair effect
- C. diagonal relationship
- D. back bonding
Explanation: Poor shielding by 4f electrons causes it.
Lanthanoid contraction
37. A major consequence of lanthanoid contraction is similarity between:
- A. Zr and Hf (Correct)
- B. Na and K
- C. Fe and Cu
- D. Li and Be
Explanation: Their radii become very similar.
Actinoids
38. Actinoids show a wider range of oxidation states mainly because:
- A. 5f, 6d, and 7s energies are comparable (Correct)
- B. they are all colorless
- C. they have no unpaired electrons
- D. they are noble gases
Explanation: More orbitals can participate in bonding.
KMnO4
39. Potassium permanganate is a strong:
- A. oxidizing agent (Correct)
- B. reducing agent only
- C. acid only
- D. polymer
Explanation: Mn in +7 state is easily reduced.
K2Cr2O7
40. Potassium dichromate is orange because chromium is in oxidation state:
- A. +6 (Correct)
- B. +3
- C. +2
- D. +7
Explanation: Dichromate contains Cr(VI).
Interstitial compounds
41. Transition metals form interstitial compounds because:
- A. small atoms occupy gaps in metal lattice (Correct)
- B. they are non-metals
- C. they lack metallic bonding
- D. they contain only s electrons
Explanation: H, C, and N can fit into interstitial sites.
Alloy
42. An alloy is a homogeneous mixture of:
- A. metals or metal with non-metal (Correct)
- B. only gases
- C. only salts
- D. only organic compounds
Explanation: Alloys modify physical properties.
Hardness
43. Transition metals generally have high enthalpy of atomization due to:
- A. strong metallic bonding from many unpaired electrons (Correct)
- B. hydrogen bonds
- C. low nuclear charge
- D. absence of d electrons
Explanation: This contributes to hardness and high melting points.
Magnetic moment
44. The spin-only magnetic moment is primarily determined by:
- A. number of unpaired electrons (Correct)
- B. number of neutrons
- C. oxidation state only
- D. mass number
Explanation: More unpaired electrons give larger moment.
Complex formation
45. Transition metals readily form complexes because they have:
- A. small size, high charge, and vacant orbitals (Correct)
- B. only large size
- C. no valence electrons
- D. low melting points
Explanation: They accept electron pairs from ligands.
d-block logic
46. The cleanest route through this chapter is to organize facts by configuration exceptions, oxidation states, color, magnetism, and:
- A. lanthanoid contraction (Correct)
- B. hybridization of methane
- C. osmotic pressure
- D. soap micelles
Explanation: That captures most repeated NEET asks.
Overall
47. The top-scoring direct questions in this chapter are electronic configurations, oxidizing agents, and:
- A. color/magnetism logic (Correct)
- B. surface adsorption
- C. gas diffusion
- D. unit-cell defects
Explanation: These are repeatedly tested.
Catalyst example
48. V$_2$O$_5$ is used as catalyst in:
- A. contact process (Correct)
- B. Haber process only
- C. Bayer process
- D. soap formation
Explanation: It catalyzes oxidation of SO$_2$ to SO$_3$.
Ferromagnetism
49. Among common first-row ions, the one with maximum unpaired electrons is often:
- A. Mn$^{2+}$ (Correct)
- B. Zn$^{2+}$
- C. Cu$^+$
- D. Sc$^{3+}$
Explanation: It has a 3d$^5$ configuration with five unpaired electrons.
Lanthanoids use
50. Cerium is a lanthanoid element of the:
- A. f-block (Correct)
- B. s-block
- C. p-block
- D. noble-gas group
Explanation: Lanthanoids occupy the f-block.
Definition
51. Transition elements generally have partially filled:
- A. d-orbitals in atom or common ion (Correct)
- B. p-orbitals only
- C. f-orbitals only
- D. s-orbitals only
Explanation: That is the accepted defining feature.
Series
52. The first transition series runs from:
- A. Sc to Zn (Correct)
- B. K to Kr
- C. La to Lu
- D. Ac to Lr
Explanation: These are the 3d elements.
Color
53. Many transition-metal compounds are colored because of:
- A. d-d electronic transitions (Correct)
- B. hydrogen bonding only
- C. complete octet
- D. lack of unpaired electrons
Explanation: Partially filled d-orbitals allow such transitions.
Oxidation state
54. Variable oxidation state in transition elements is due to similar energies of:
- A. ns and (n-1)d electrons (Correct)
- B. 1s and 2p electrons
- C. f and g orbitals
- D. only p electrons
Explanation: Both sets may participate in bonding.
Catalysis
55. Transition metals often act as good catalysts because they show:
- A. variable oxidation state and adsorption ability (Correct)
- B. only low density
- C. only high electronegativity
- D. always +1 state
Explanation: Surface behavior and redox flexibility help catalysis.
Magnetism
56. Paramagnetism in transition-metal ions is due to:
- A. unpaired electrons (Correct)
- B. paired electrons only
- C. empty shells only
- D. hydrogen bonding
Explanation: Magnetic moment depends on the count of unpaired electrons.
Scandium
57. Among Sc, Ti, V, Cr, Mn, the highest oxidation state is shown by:
- A. Mn (Correct)
- B. Sc
- C. Ti
- D. Cr only
Explanation: Mn reaches +7 in permanganate.
Chromium
58. Electronic configuration of chromium is exceptional because it is:
- A. [Ar] 3d$^5$ 4s$^1$ (Correct)
- B. [Ar] 3d$^4$ 4s$^2$
- C. [Ar] 3d$^6$ 4s$^0$
- D. [Ar] 3d$^3$ 4s$^3$
Explanation: Half-filled d-subshell stability causes the exception.
Copper
59. Electronic configuration of copper is:
- A. [Ar] 3d$^{10}$ 4s$^1$ (Correct)
- B. [Ar] 3d$^9$ 4s$^2$
- C. [Ar] 3d$^8$ 4s$^3$
- D. [Ar] 3d$^{10}$ 4s$^2$
Explanation: Filled d-subshell gives extra stability.
Ion color
60. Zn$^{2+}$ compounds are generally colorless because Zn$^{2+}$ has:
- A. completely filled d-subshell (Correct)
- B. empty p-subshell
- C. high hydration only
- D. no nucleus
Explanation: No d-d transitions are possible.
Lanthanoids
61. The progressive decrease in size across lanthanoids is called:
- A. lanthanoid contraction (Correct)
- B. inert pair effect
- C. diagonal relationship
- D. back bonding
Explanation: Poor shielding by 4f electrons causes it.
Lanthanoid contraction
62. A major consequence of lanthanoid contraction is similarity between:
- A. Zr and Hf (Correct)
- B. Na and K
- C. Fe and Cu
- D. Li and Be
Explanation: Their radii become very similar.
Actinoids
63. Actinoids show a wider range of oxidation states mainly because:
- A. 5f, 6d, and 7s energies are comparable (Correct)
- B. they are all colorless
- C. they have no unpaired electrons
- D. they are noble gases
Explanation: More orbitals can participate in bonding.
KMnO4
64. Potassium permanganate is a strong:
- A. oxidizing agent (Correct)
- B. reducing agent only
- C. acid only
- D. polymer
Explanation: Mn in +7 state is easily reduced.
K2Cr2O7
65. Potassium dichromate is orange because chromium is in oxidation state:
- A. +6 (Correct)
- B. +3
- C. +2
- D. +7
Explanation: Dichromate contains Cr(VI).
Interstitial compounds
66. Transition metals form interstitial compounds because:
- A. small atoms occupy gaps in metal lattice (Correct)
- B. they are non-metals
- C. they lack metallic bonding
- D. they contain only s electrons
Explanation: H, C, and N can fit into interstitial sites.
Alloy
67. An alloy is a homogeneous mixture of:
- A. metals or metal with non-metal (Correct)
- B. only gases
- C. only salts
- D. only organic compounds
Explanation: Alloys modify physical properties.
Hardness
68. Transition metals generally have high enthalpy of atomization due to:
- A. strong metallic bonding from many unpaired electrons (Correct)
- B. hydrogen bonds
- C. low nuclear charge
- D. absence of d electrons
Explanation: This contributes to hardness and high melting points.
Magnetic moment
69. The spin-only magnetic moment is primarily determined by:
- A. number of unpaired electrons (Correct)
- B. number of neutrons
- C. oxidation state only
- D. mass number
Explanation: More unpaired electrons give larger moment.
Complex formation
70. Transition metals readily form complexes because they have:
- A. small size, high charge, and vacant orbitals (Correct)
- B. only large size
- C. no valence electrons
- D. low melting points
Explanation: They accept electron pairs from ligands.
d-block logic
71. The cleanest route through this chapter is to organize facts by configuration exceptions, oxidation states, color, magnetism, and:
- A. lanthanoid contraction (Correct)
- B. hybridization of methane
- C. osmotic pressure
- D. soap micelles
Explanation: That captures most repeated NEET asks.
Overall
72. The top-scoring direct questions in this chapter are electronic configurations, oxidizing agents, and:
- A. color/magnetism logic (Correct)
- B. surface adsorption
- C. gas diffusion
- D. unit-cell defects
Explanation: These are repeatedly tested.
Catalyst example
73. V$_2$O$_5$ is used as catalyst in:
- A. contact process (Correct)
- B. Haber process only
- C. Bayer process
- D. soap formation
Explanation: It catalyzes oxidation of SO$_2$ to SO$_3$.
Ferromagnetism
74. Among common first-row ions, the one with maximum unpaired electrons is often:
- A. Mn$^{2+}$ (Correct)
- B. Zn$^{2+}$
- C. Cu$^+$
- D. Sc$^{3+}$
Explanation: It has a 3d$^5$ configuration with five unpaired electrons.
Lanthanoids use
75. Cerium is a lanthanoid element of the:
- A. f-block (Correct)
- B. s-block
- C. p-block
- D. noble-gas group
Explanation: Lanthanoids occupy the f-block.
Definition
76. Transition elements generally have partially filled:
- A. d-orbitals in atom or common ion (Correct)
- B. p-orbitals only
- C. f-orbitals only
- D. s-orbitals only
Explanation: That is the accepted defining feature.
Series
77. The first transition series runs from:
- A. Sc to Zn (Correct)
- B. K to Kr
- C. La to Lu
- D. Ac to Lr
Explanation: These are the 3d elements.
Color
78. Many transition-metal compounds are colored because of:
- A. d-d electronic transitions (Correct)
- B. hydrogen bonding only
- C. complete octet
- D. lack of unpaired electrons
Explanation: Partially filled d-orbitals allow such transitions.
Oxidation state
79. Variable oxidation state in transition elements is due to similar energies of:
- A. ns and (n-1)d electrons (Correct)
- B. 1s and 2p electrons
- C. f and g orbitals
- D. only p electrons
Explanation: Both sets may participate in bonding.
Catalysis
80. Transition metals often act as good catalysts because they show:
- A. variable oxidation state and adsorption ability (Correct)
- B. only low density
- C. only high electronegativity
- D. always +1 state
Explanation: Surface behavior and redox flexibility help catalysis.
Magnetism
81. Paramagnetism in transition-metal ions is due to:
- A. unpaired electrons (Correct)
- B. paired electrons only
- C. empty shells only
- D. hydrogen bonding
Explanation: Magnetic moment depends on the count of unpaired electrons.
Scandium
82. Among Sc, Ti, V, Cr, Mn, the highest oxidation state is shown by:
- A. Mn (Correct)
- B. Sc
- C. Ti
- D. Cr only
Explanation: Mn reaches +7 in permanganate.
Chromium
83. Electronic configuration of chromium is exceptional because it is:
- A. [Ar] 3d$^5$ 4s$^1$ (Correct)
- B. [Ar] 3d$^4$ 4s$^2$
- C. [Ar] 3d$^6$ 4s$^0$
- D. [Ar] 3d$^3$ 4s$^3$
Explanation: Half-filled d-subshell stability causes the exception.
Copper
84. Electronic configuration of copper is:
- A. [Ar] 3d$^{10}$ 4s$^1$ (Correct)
- B. [Ar] 3d$^9$ 4s$^2$
- C. [Ar] 3d$^8$ 4s$^3$
- D. [Ar] 3d$^{10}$ 4s$^2$
Explanation: Filled d-subshell gives extra stability.
Ion color
85. Zn$^{2+}$ compounds are generally colorless because Zn$^{2+}$ has:
- A. completely filled d-subshell (Correct)
- B. empty p-subshell
- C. high hydration only
- D. no nucleus
Explanation: No d-d transitions are possible.
Lanthanoids
86. The progressive decrease in size across lanthanoids is called:
- A. lanthanoid contraction (Correct)
- B. inert pair effect
- C. diagonal relationship
- D. back bonding
Explanation: Poor shielding by 4f electrons causes it.
Lanthanoid contraction
87. A major consequence of lanthanoid contraction is similarity between:
- A. Zr and Hf (Correct)
- B. Na and K
- C. Fe and Cu
- D. Li and Be
Explanation: Their radii become very similar.
Actinoids
88. Actinoids show a wider range of oxidation states mainly because:
- A. 5f, 6d, and 7s energies are comparable (Correct)
- B. they are all colorless
- C. they have no unpaired electrons
- D. they are noble gases
Explanation: More orbitals can participate in bonding.
KMnO4
89. Potassium permanganate is a strong:
- A. oxidizing agent (Correct)
- B. reducing agent only
- C. acid only
- D. polymer
Explanation: Mn in +7 state is easily reduced.
K2Cr2O7
90. Potassium dichromate is orange because chromium is in oxidation state:
- A. +6 (Correct)
- B. +3
- C. +2
- D. +7
Explanation: Dichromate contains Cr(VI).
Interstitial compounds
91. Transition metals form interstitial compounds because:
- A. small atoms occupy gaps in metal lattice (Correct)
- B. they are non-metals
- C. they lack metallic bonding
- D. they contain only s electrons
Explanation: H, C, and N can fit into interstitial sites.
Alloy
92. An alloy is a homogeneous mixture of:
- A. metals or metal with non-metal (Correct)
- B. only gases
- C. only salts
- D. only organic compounds
Explanation: Alloys modify physical properties.
Hardness
93. Transition metals generally have high enthalpy of atomization due to:
- A. strong metallic bonding from many unpaired electrons (Correct)
- B. hydrogen bonds
- C. low nuclear charge
- D. absence of d electrons
Explanation: This contributes to hardness and high melting points.
Magnetic moment
94. The spin-only magnetic moment is primarily determined by:
- A. number of unpaired electrons (Correct)
- B. number of neutrons
- C. oxidation state only
- D. mass number
Explanation: More unpaired electrons give larger moment.
Complex formation
95. Transition metals readily form complexes because they have:
- A. small size, high charge, and vacant orbitals (Correct)
- B. only large size
- C. no valence electrons
- D. low melting points
Explanation: They accept electron pairs from ligands.
d-block logic
96. The cleanest route through this chapter is to organize facts by configuration exceptions, oxidation states, color, magnetism, and:
- A. lanthanoid contraction (Correct)
- B. hybridization of methane
- C. osmotic pressure
- D. soap micelles
Explanation: That captures most repeated NEET asks.
Overall
97. The top-scoring direct questions in this chapter are electronic configurations, oxidizing agents, and:
- A. color/magnetism logic (Correct)
- B. surface adsorption
- C. gas diffusion
- D. unit-cell defects
Explanation: These are repeatedly tested.
Catalyst example
98. V$_2$O$_5$ is used as catalyst in:
- A. contact process (Correct)
- B. Haber process only
- C. Bayer process
- D. soap formation
Explanation: It catalyzes oxidation of SO$_2$ to SO$_3$.
Ferromagnetism
99. Among common first-row ions, the one with maximum unpaired electrons is often:
- A. Mn$^{2+}$ (Correct)
- B. Zn$^{2+}$
- C. Cu$^+$
- D. Sc$^{3+}$
Explanation: It has a 3d$^5$ configuration with five unpaired electrons.
Lanthanoids use
100. Cerium is a lanthanoid element of the:
- A. f-block (Correct)
- B. s-block
- C. p-block
- D. noble-gas group
Explanation: Lanthanoids occupy the f-block.
Definition
101. Transition elements generally have partially filled:
- A. d-orbitals in atom or common ion (Correct)
- B. p-orbitals only
- C. f-orbitals only
- D. s-orbitals only
Explanation: That is the accepted defining feature.
Series
102. The first transition series runs from:
- A. Sc to Zn (Correct)
- B. K to Kr
- C. La to Lu
- D. Ac to Lr
Explanation: These are the 3d elements.
Color
103. Many transition-metal compounds are colored because of:
- A. d-d electronic transitions (Correct)
- B. hydrogen bonding only
- C. complete octet
- D. lack of unpaired electrons
Explanation: Partially filled d-orbitals allow such transitions.
Oxidation state
104. Variable oxidation state in transition elements is due to similar energies of:
- A. ns and (n-1)d electrons (Correct)
- B. 1s and 2p electrons
- C. f and g orbitals
- D. only p electrons
Explanation: Both sets may participate in bonding.
Catalysis
105. Transition metals often act as good catalysts because they show:
- A. variable oxidation state and adsorption ability (Correct)
- B. only low density
- C. only high electronegativity
- D. always +1 state
Explanation: Surface behavior and redox flexibility help catalysis.
Magnetism
106. Paramagnetism in transition-metal ions is due to:
- A. unpaired electrons (Correct)
- B. paired electrons only
- C. empty shells only
- D. hydrogen bonding
Explanation: Magnetic moment depends on the count of unpaired electrons.
Scandium
107. Among Sc, Ti, V, Cr, Mn, the highest oxidation state is shown by:
- A. Mn (Correct)
- B. Sc
- C. Ti
- D. Cr only
Explanation: Mn reaches +7 in permanganate.
Chromium
108. Electronic configuration of chromium is exceptional because it is:
- A. [Ar] 3d$^5$ 4s$^1$ (Correct)
- B. [Ar] 3d$^4$ 4s$^2$
- C. [Ar] 3d$^6$ 4s$^0$
- D. [Ar] 3d$^3$ 4s$^3$
Explanation: Half-filled d-subshell stability causes the exception.
Copper
109. Electronic configuration of copper is:
- A. [Ar] 3d$^{10}$ 4s$^1$ (Correct)
- B. [Ar] 3d$^9$ 4s$^2$
- C. [Ar] 3d$^8$ 4s$^3$
- D. [Ar] 3d$^{10}$ 4s$^2$
Explanation: Filled d-subshell gives extra stability.
Ion color
110. Zn$^{2+}$ compounds are generally colorless because Zn$^{2+}$ has:
- A. completely filled d-subshell (Correct)
- B. empty p-subshell
- C. high hydration only
- D. no nucleus
Explanation: No d-d transitions are possible.
Lanthanoids
111. The progressive decrease in size across lanthanoids is called:
- A. lanthanoid contraction (Correct)
- B. inert pair effect
- C. diagonal relationship
- D. back bonding
Explanation: Poor shielding by 4f electrons causes it.
Lanthanoid contraction
112. A major consequence of lanthanoid contraction is similarity between:
- A. Zr and Hf (Correct)
- B. Na and K
- C. Fe and Cu
- D. Li and Be
Explanation: Their radii become very similar.
Actinoids
113. Actinoids show a wider range of oxidation states mainly because:
- A. 5f, 6d, and 7s energies are comparable (Correct)
- B. they are all colorless
- C. they have no unpaired electrons
- D. they are noble gases
Explanation: More orbitals can participate in bonding.
KMnO4
114. Potassium permanganate is a strong:
- A. oxidizing agent (Correct)
- B. reducing agent only
- C. acid only
- D. polymer
Explanation: Mn in +7 state is easily reduced.
K2Cr2O7
115. Potassium dichromate is orange because chromium is in oxidation state:
- A. +6 (Correct)
- B. +3
- C. +2
- D. +7
Explanation: Dichromate contains Cr(VI).
Interstitial compounds
116. Transition metals form interstitial compounds because:
- A. small atoms occupy gaps in metal lattice (Correct)
- B. they are non-metals
- C. they lack metallic bonding
- D. they contain only s electrons
Explanation: H, C, and N can fit into interstitial sites.
Alloy
117. An alloy is a homogeneous mixture of:
- A. metals or metal with non-metal (Correct)
- B. only gases
- C. only salts
- D. only organic compounds
Explanation: Alloys modify physical properties.
Hardness
118. Transition metals generally have high enthalpy of atomization due to:
- A. strong metallic bonding from many unpaired electrons (Correct)
- B. hydrogen bonds
- C. low nuclear charge
- D. absence of d electrons
Explanation: This contributes to hardness and high melting points.
Magnetic moment
119. The spin-only magnetic moment is primarily determined by:
- A. number of unpaired electrons (Correct)
- B. number of neutrons
- C. oxidation state only
- D. mass number
Explanation: More unpaired electrons give larger moment.
Complex formation
120. Transition metals readily form complexes because they have:
- A. small size, high charge, and vacant orbitals (Correct)
- B. only large size
- C. no valence electrons
- D. low melting points
Explanation: They accept electron pairs from ligands.
d-block logic
121. The cleanest route through this chapter is to organize facts by configuration exceptions, oxidation states, color, magnetism, and:
- A. lanthanoid contraction (Correct)
- B. hybridization of methane
- C. osmotic pressure
- D. soap micelles
Explanation: That captures most repeated NEET asks.
Overall
122. The top-scoring direct questions in this chapter are electronic configurations, oxidizing agents, and:
- A. color/magnetism logic (Correct)
- B. surface adsorption
- C. gas diffusion
- D. unit-cell defects
Explanation: These are repeatedly tested.
Catalyst example
123. V$_2$O$_5$ is used as catalyst in:
- A. contact process (Correct)
- B. Haber process only
- C. Bayer process
- D. soap formation
Explanation: It catalyzes oxidation of SO$_2$ to SO$_3$.
Ferromagnetism
124. Among common first-row ions, the one with maximum unpaired electrons is often:
- A. Mn$^{2+}$ (Correct)
- B. Zn$^{2+}$
- C. Cu$^+$
- D. Sc$^{3+}$
Explanation: It has a 3d$^5$ configuration with five unpaired electrons.
Lanthanoids use
125. Cerium is a lanthanoid element of the:
- A. f-block (Correct)
- B. s-block
- C. p-block
- D. noble-gas group
Explanation: Lanthanoids occupy the f-block.

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