1. Who is known as the father of the modern periodic table?
A) Mendeleev
B) Moseley
C) Dobereiner
D) Newlands
Answer: A
Explanation: Dmitri Mendeleev arranged elements based on increasing atomic mass and their properties.
2. Dobereiner’s law of triads was based on:
A) Atomic number
B) Atomic mass
C) Valency
D) Isotopes
Answer: B
Explanation: He grouped elements into triads where the atomic mass of the middle element was approximately the average of the other two.
3. Newlands’ Law of Octaves stated:
A) Every 8th element repeats properties
B) Every 7th element repeats properties
C) Properties depend on valency
D) Elements are arranged in triads
Answer: A
Explanation: Newlands observed periodic repetition of properties after every 8th element.
4. Limitation of Newlands’ law of octaves:
A) Worked only up to calcium
B) Did not consider isotopes
C) Couldn’t explain noble gases
D) All of the above
Answer: D
Explanation: Octaves failed for elements beyond calcium and ignored isotopes/noble gases.
5. Mendeleev arranged elements on the basis of:
A) Increasing atomic mass
B) Increasing atomic number
C) Atomic size
D) Electronegativity
Answer: A
Explanation: Mendeleev used atomic mass as the basis, later corrected by Moseley.
6. Mendeleev left gaps in his table for:
A) Noble gases
B) Unknown elements
C) Isotopes
D) Transition metals
Answer: B
Explanation: He predicted properties of undiscovered elements like Eka-aluminium (Gallium).
7. Modern periodic law was given by:
A) Mendeleev
B) Moseley
C) Dalton
D) Rutherford
Answer: B
Explanation: Moseley stated that properties of elements depend on atomic number, not atomic mass.
8. Which law forms the basis of the modern periodic table?
A) Law of octaves
B) Mendeleev’s law
C) Modern periodic law
D) Law of constant proportion
Answer: C
Explanation: Moseley’s modern periodic law is the foundation of today’s periodic table.
9. Noble gases were not included in Mendeleev’s periodic table because:
A) They were not discovered
B) They are inert
C) They do not follow octaves
D) Their mass was unknown
Answer: A
Explanation: Noble gases were discovered later (1894 onwards).
10. Eka-silicon predicted by Mendeleev was later discovered as:
A) Germanium
B) Gallium
C) Silicon
D) Tin
Answer: A
Explanation: Eka-silicon was Germanium (Ge).
11. Eka-aluminium predicted by Mendeleev was:
A) Indium
B) Gallium
C) Thallium
D) Aluminium
Answer: B
Explanation: Eka-aluminium turned out to be Gallium.
12. The limitation of Mendeleev’s periodic table was:
A) Position of isotopes
B) Position of hydrogen
C) Anomalous mass order
D) All of the above
Answer: D
Explanation: Isotopes and hydrogen could not be placed properly.
13. Who discovered the atomic number?
A) Moseley
B) Bohr
C) Mendeleev
D) Dalton
Answer: A
Explanation: Henry Moseley discovered atomic number using X-ray spectra.
14. How many elements were known at the time of Mendeleev?
A) 56
B) 63
C) 72
D) 92
Answer: B
Explanation: Mendeleev worked with 63 known elements.
15. Modern periodic law states that:
A) Properties depend on atomic mass
B) Properties depend on atomic number
C) Properties depend on valency
D) Properties depend on isotopes
Answer: B
Explanation: Atomic number determines properties, not mass.
16. Which element challenged Mendeleev’s arrangement?
A) Argon & Potassium
B) Cobalt & Nickel
C) Tellurium & Iodine
D) All of the above
Answer: D
Explanation: Mass order and properties conflicted in these cases.
17. The modern periodic table was first prepared by:
A) Mendeleev
B) Moseley
C) Bohr
D) Seaborg
Answer: C
Explanation: Bohr prepared a long form of the periodic table.
18. Noble gases were discovered by:
A) William Ramsay
B) Moseley
C) Mendeleev
D) Bohr
Answer: A
Explanation: Ramsay discovered noble gases (1894 onwards).
19. Which element was not discovered during Mendeleev’s time?
A) Gallium
B) Argon
C) Germanium
D) Scandium
Answer: B
Explanation: Argon was discovered later in 1894.
20. Triads concept was proposed by:
A) Dobereiner
B) Newlands
C) Mendeleev
D) Moseley
Answer: A
Explanation: Dobereiner’s triads grouped elements in threes.
21. Which element does not fit into Dobereiner’s triads?
A) Cl, Br, I
B) Li, Na, K
C) Ca, Sr, Ba
D) H, He, Li
Answer: D
Explanation: H, He, Li do not follow the triad rule.
22. Newlands’ law of octaves failed because:
A) He placed two elements in one slot
B) Did not leave space for undiscovered elements
C) Worked only up to calcium
D) All of the above
Answer: D
Explanation: These were major drawbacks.
23. Which property did Mendeleev not consider while arranging elements?
A) Oxides
B) Hydrides
C) Atomic number
D) Atomic mass
Answer: C
Explanation: Atomic number was not discovered then.
24. Which two elements were placed together despite different atomic masses by Mendeleev?
A) Co and Ni
B) Ar and K
C) Te and I
D) All of these
Answer: D
Explanation: Such anomalies occurred in his table.
25. The long form of the periodic table is also called:
A) Mendeleev’s table
B) Bohr’s table
C) Modern periodic table
D) Octave table
Answer: C
Explanation: The long form (modern) periodic table is widely used today.
26. The modern periodic table is based on:
A) Atomic mass
B) Atomic number
C) Valency
D) Isotopes
Answer: B
Explanation: Moseley showed that atomic number determines properties of elements.
27. How many periods are there in the modern periodic table?
A) 7
B) 8
C) 9
D) 6
Answer: A
Explanation: The periodic table has 7 horizontal periods.
28. How many groups are present in the modern periodic table?
A) 7
B) 8
C) 18
D) 9
Answer: C
Explanation: The modern periodic table consists of 18 vertical groups.
29. The elements of group 18 are called:
A) Halogens
B) Alkali metals
C) Noble gases
D) Transition elements
Answer: C
Explanation: Group 18 elements are noble gases with stable electronic configurations.
30. The elements of group 17 are known as:
A) Chalcogens
B) Halogens
C) Noble gases
D) Alkali metals
Answer: B
Explanation: Group 17 elements (F, Cl, Br, I, At) are halogens.
31. The elements of group 1 are:
A) Alkali metals
B) Alkaline earth metals
C) Transition metals
D) Noble gases
Answer: A
Explanation: Group 1 elements (Li, Na, K, etc.) are called alkali metals.
32. Group 2 elements are called:
A) Alkali metals
B) Alkaline earth metals
C) Halogens
D) Noble gases
Answer: B
Explanation: Group 2 elements (Be, Mg, Ca, etc.) are alkaline earth metals.
33. Which period contains the maximum number of elements?
A) 1st
B) 2nd
C) 6th
D) 7th
Answer: C
Explanation: The 6th period has 32 elements including lanthanides.
34. Which of the following elements belongs to group 16?
A) Nitrogen
B) Oxygen
C) Chlorine
D) Sodium
Answer: B
Explanation: Oxygen family (O, S, Se, Te, Po) are group 16 elements (chalcogens).
35. Which is the first element of the modern periodic table?
A) Hydrogen
B) Helium
C) Lithium
D) Beryllium
Answer: A
Explanation: Hydrogen (Z = 1) is the first element.
36. Which is the last naturally occurring element in the periodic table?
A) Uranium
B) Thorium
C) Plutonium
D) Fermium
Answer: A
Explanation: Uranium (Z = 92) is the last naturally occurring element.
37. Which element has the highest electronegativity?
A) Oxygen
B) Fluorine
C) Chlorine
D) Nitrogen
Answer: B
Explanation: Fluorine (EN = 3.98) is the most electronegative element.
38. In a period, atomic size generally:
A) Increases from left to right
B) Decreases from left to right
C) Remains constant
D) Increases and then decreases
Answer: B
Explanation: Across a period, nuclear charge increases, pulling electrons closer.
39. In a group, atomic size generally:
A) Increases down the group
B) Decreases down the group
C) Remains constant
D) First decreases then increases
Answer: A
Explanation: New shells are added down the group, increasing atomic radius.
40. Ionization energy across a period generally:
A) Decreases
B) Increases
C) Remains constant
D) Random
Answer: B
Explanation: More nuclear charge across a period increases ionization energy.
41. Ionization energy down a group:
A) Increases
B) Decreases
C) Remains constant
D) Increases irregularly
Answer: B
Explanation: Larger atomic size and shielding effect lower ionization energy.
42. Electron affinity across a period generally:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Smaller size and higher nuclear charge increase electron affinity across a period.
43. Electron affinity down a group:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: B
Explanation: Larger size reduces effective attraction for extra electrons.
44. Metallic character across a period:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: B
Explanation: Across a period, tendency to lose electrons decreases → less metallic.
45. Metallic character down a group:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Down a group, larger atoms lose electrons easily → more metallic.
46. Non-metallic character across a period:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Across a period, tendency to gain electrons increases.
47. Which group is also called “alkali metals”?
A) Group 2
B) Group 1
C) Group 13
D) Group 18
Answer: B
Explanation: Group 1 metals (Li, Na, K) form strong alkalis with water.
48. The most metallic element is:
A) Cesium
B) Sodium
C) Francium
D) Potassium
Answer: C
Explanation: Francium is the most metallic (least electronegative, lowest ionization energy).
49. The most non-metallic element is:
A) Fluorine
B) Oxygen
C) Chlorine
D) Nitrogen
Answer: A
Explanation: Fluorine has highest non-metallic nature due to high electronegativity.
50. Which element has the smallest atomic radius?
A) Hydrogen
B) Helium
C) Lithium
D) Fluorine
Answer: B
Explanation: Helium has the smallest atomic size because of its high nuclear charge and no shielding.
51. First ionization energy is defined as:
A) Energy required to remove an electron from a cation
B) Energy released when an electron is added to an atom
C) Energy required to remove one electron from a neutral atom
D) Energy required to remove a proton
Answer: C
Explanation: First ionization energy (IE₁) is the energy needed to remove one electron from a neutral gaseous atom.
52. Second ionization energy is:
A) Always smaller than the first
B) Equal to the first
C) Always greater than the first
D) None of these
Answer: C
Explanation: Removing a second electron is harder due to increased effective nuclear charge.
53. Across a period, ionization energy:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Nuclear charge increases → electrons are held tightly → higher IE.
54. Down a group, ionization energy:
A) Increases
B) Decreases
C) Remains constant
D) Varies randomly
Answer: B
Explanation: Electrons are farther from nucleus and shielding increases → IE decreases.
55. Electronegativity of an element:
A) Tendency to donate electrons
B) Tendency to attract bonding electrons
C) Tendency to lose protons
D) None of these
Answer: B
Explanation: Electronegativity measures how strongly an atom attracts shared electrons in a bond.
56. Electronegativity across a period:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Nuclear charge increases, atomic size decreases → stronger attraction for electrons.
57. Electronegativity down a group:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: B
Explanation: Larger atoms → bonding electrons are farther from nucleus → lower electronegativity.
58. Atomic size across a period:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: B
Explanation: Nuclear charge increases → electrons pulled closer → smaller size.
59. Atomic size down a group:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Extra electron shells increase the size despite nuclear charge.
60. Cation size is:
A) Larger than neutral atom
B) Smaller than neutral atom
C) Same as neutral atom
D) Random
Answer: B
Explanation: Cations have fewer electrons → smaller radius due to less electron–electron repulsion.
61. Anion size is:
A) Larger than neutral atom
B) Smaller than neutral atom
C) Same as neutral atom
D) Random
Answer: A
Explanation: Extra electrons increase repulsion → larger radius.
62. Metallic character across a period:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: B
Explanation: Tendency to lose electrons decreases → less metallic.
63. Metallic character down a group:
A) Increases
B) Decreases
C) Remains constant
D) Random
Answer: A
Explanation: Larger atoms lose electrons easily → more metallic.
64. Which type of oxides are formed by metals?
A) Acidic
B) Basic
C) Amphoteric
D) Neutral
Answer: B
Explanation: Metals react with oxygen to form basic oxides (e.g., Na₂O, CaO).
65. Which type of oxides are formed by non-metals?
A) Acidic
B) Basic
C) Amphoteric
D) Neutral
Answer: A
Explanation: Non-metals form acidic oxides (e.g., CO₂, SO₂).
66. Amphoteric oxides show:
A) Acidic behavior only
B) Basic behavior only
C) Both acidic and basic behavior
D) None
Answer: C
Explanation: Oxides like Al₂O₃ and ZnO react with both acids and bases.
67. Oxides of elements in period 3 show:
A) All basic
B) All acidic
C) Basic → Amphoteric → Acidic trend
D) Random
Answer: C
Explanation: Na₂O, MgO → basic; Al₂O₃ → amphoteric; SiO₂, P₄O₁₀ → acidic.
68. Oxides of halogens are:
A) Basic
B) Acidic
C) Amphoteric
D) Neutral
Answer: B
Explanation: Non-metal halogen oxides (Cl₂O, Cl₂O₇) are acidic.
69. Ionization energy of noble gases is:
A) Very low
B) Very high
C) Moderate
D) Variable
Answer: B
Explanation: Noble gases have full valence shells → very stable → high IE.
70. Fluorine is most reactive because:
A) Small size & high electronegativity
B) Large size
C) Low ionization energy
D) None
Answer: A
Explanation: High electronegativity and small radius → reacts vigorously.
71. Alkali metals are highly reactive because:
A) High electronegativity
B) Low ionization energy
C) Small size
D) High electron affinity
Answer: B
Explanation: Easily lose outer electron → high reactivity.
72. Most electronegative element in period 2 is:
A) Li
B) C
C) O
D) F
Answer: D
Explanation: Fluorine has the highest electronegativity (3.98).
73. Hydrogen is placed in group 1 because:
A) It has 1 electron in valence shell
B) It forms cations
C) It behaves like alkali metal in reactions
D) All of these
Answer: D
Explanation: Hydrogen shares properties of group 1 (valence e⁻, cation formation).
74. Hydrogen is placed in group 17 in some tables because:
A) It forms H⁻ ions
B) It behaves like halogen
C) Both A & B
D) None
Answer: C
Explanation: Hydrogen can gain one electron → forms hydride (H⁻), similar to halogens.
75. Most acidic oxide among period 3 elements is:
A) Na₂O
B) MgO
C) SiO₂
D) P₄O₁₀
Answer: D
Explanation: P₄O₁₀ is strongly acidic → reacts with water to form H₃PO₄.
76. Transition elements are characterized by:
A) Partially filled d-orbitals
B) Partially filled p-orbitals
C) Completely filled s-orbitals only
D) Fully filled d-orbitals
Answer: A
Explanation: Transition metals have incomplete d-orbitals in their ground or common oxidation state.
77. Which of the following is a transition metal?
A) Scandium (Sc)
B) Sodium (Na)
C) Magnesium (Mg)
D) Calcium (Ca)
Answer: A
Explanation: Scandium has partially filled d-orbitals → transition element.
78. Which of the following is not a transition element?
A) Zinc (Zn)
B) Iron (Fe)
C) Copper (Cu)
D) Titanium (Ti)
Answer: A
Explanation: Zn has fully filled 3d¹⁰ orbitals → not a true transition element.
79. Common oxidation states of transition metals are:
A) Only +1
B) +2 and +3 (variable)
C) Only +2
D) Only +3
Answer: B
Explanation: Transition metals exhibit variable oxidation states due to involvement of (n–1)d and ns electrons.
80. Which of the following elements shows +6 oxidation state?
A) Chromium
B) Iron
C) Copper
D) Zinc
Answer: A
Explanation: Chromium forms CrO₃ → oxidation state +6.
81. Which transition element forms colored compounds?
A) Titanium
B) Vanadium
C) Copper
D) All of these
Answer: D
Explanation: Partially filled d-orbitals → d–d transitions → colored compounds.
82. Transition elements often exhibit:
A) Magnetic properties
B) Catalytic behavior
C) Formation of complex compounds
D) All of these
Answer: D
Explanation: Variable oxidation states and unpaired electrons enable these properties.
83. Lanthanides are also called:
A) Rare earth elements
B) Noble gases
C) Alkali metals
D) Actinides
Answer: A
Explanation: Lanthanides (Ce–Lu) are known as rare earth elements.
84. The general electronic configuration of lanthanides is:
A) [Xe] 4fⁿ5d⁰6s²
B) [Xe] 5dⁿ6s²
C) [Xe] 4dⁿ5s²
D) [Xe] 3dⁿ4s²
Answer: A
Explanation: Lanthanides fill 4f orbitals (4fⁿ5d⁰6s²).
85. Actinides are characterized by:
A) Filling 5f orbitals
B) Filling 4f orbitals
C) Filling 3d orbitals
D) Filling 6d orbitals
Answer: A
Explanation: Actinides (Th–Lr) have filling of 5f orbitals.
86. Which actinide is used as fuel in nuclear reactors?
A) Uranium
B) Thorium
C) Plutonium
D) All of these
Answer: D
Explanation: U, Th, and Pu isotopes are used as nuclear fuel.
87. Transition metals act as good catalysts because:
A) They are colored
B) They have variable oxidation states
C) They are hard metals
D) They are dense
Answer: B
Explanation: Variable oxidation states allow them to facilitate reactions without being consumed.
88. Most stable oxidation state of Zn is:
A) +1
B) +2
C) +3
D) 0
Answer: B
Explanation: Zn forms only +2 because d-orbitals are completely filled.
89. Elements showing f-block contraction:
A) Lanthanides
B) Actinides
C) Both A & B
D) Transition elements
Answer: C
Explanation: Poor shielding by f-electrons → contraction in size across series.
90. The common oxidation state of cerium (Ce) is:
A) +2
B) +3
C) +4
D) +6
Answer: C
Explanation: Ce exhibits both +3 and +4 states; +4 is common in CeO₂.
91. Transition metals form colored ions due to:
A) f–f transitions
B) d–d transitions
C) s–s transitions
D) p–p transitions
Answer: B
Explanation: Partially filled d-orbitals allow electronic transitions → color.
92. Which element is used in making blue pigment?
A) Copper
B) Cobalt
C) Nickel
D) Titanium
Answer: B
Explanation: Cobalt compounds (Co²⁺) give blue color in glass and ceramics.
93. Which property is enhanced due to transition metals’ unpaired electrons?
A) Paramagnetism
B) Density
C) Atomic radius
D) Ionization energy
Answer: A
Explanation: Unpaired d-electrons lead to paramagnetic behavior.
94. Oxides of transition elements are generally:
A) Basic
B) Amphoteric
C) Acidic
D) Neutral
Answer: B
Explanation: Many oxides (ZnO, Al₂O₃, Cr₂O₃) react with both acids and bases.
95. Most stable oxidation state of manganese is:
A) +2
B) +4
C) +7
D) +3
Answer: A
Explanation: Mn²⁺ (d⁵) is stable due to half-filled d-orbital stability.
96. Which lanthanide is used in making strong permanent magnets?
A) Neodymium
B) Cerium
C) Samarium
D) Europium
Answer: A
Explanation: Nd₂Fe₁₄B magnets are very strong due to Nd³⁺ ions.
97. Which actinide is used in nuclear weapons?
A) Uranium-235
B) Thorium
C) Neptunium
D) Plutonium-239
Answer: D
Explanation: Plutonium-239 is fissile → used in nuclear weapons.
98. Which element shows variable oxidation states from +2 to +7?
A) Chromium
B) Iron
C) Copper
D) Zinc
Answer: A
Explanation: Cr forms Cr²⁺, Cr³⁺, Cr⁶⁺, etc.
99. Transition metals are less reactive than alkali metals because:
A) They have higher ionization energy
B) They have variable oxidation states
C) They have d-electrons
D) All of these
Answer: D
Explanation: Higher IE and d-electrons reduce their tendency to lose electrons rapidly.
100. The most important application of transition metals is:
A) Industrial catalysis
B) Jewelry
C) Nuclear fuel
D) Household cleaning
Answer: A
Explanation: Transition metals (Fe, Pt, Ni, etc.) are widely used as catalysts in industry.