Basic Concepts of Chemistry (10 Questions)
1. What is the SI unit of amount of substance?
A) Kilogram
B) Gram
C) Mole
D) Liter
2. The number of atoms in one mole of an element is equal to:
A) 6.022 × 10²²
B) 6.022 × 10²³
C) 6.022 × 10²⁴
D) 6.022 × 10²⁵
3. Which law states that the total mass of reactants equals the total mass of products?
A) Law of Conservation of Mass
B) Law of Definite Proportions
C) Law of Multiple Proportions
D) Avogadro’s Law
4. The molecular mass of CO₂ is:
A) 32 u
B) 28 u
C) 40 u
D) 44 u
5. The empirical formula of a compound with 40% carbon, 6.67% hydrogen, and 53.33% oxygen is:
A) C₂H₄O₂
B) CH₂O
C) C₃H₆O₃
D) CHO
6. One mole of any gas at STP occupies:
A) 11.2 L
B) 22.0 L
C) 22.4 L
D) 44.8 L
7. The number of significant figures in 0.00250 is:
A) 3
B) 4
C) 5
D) 2
8. What is the percentage composition of carbon in C₆H₁₂O₆?
A) 50%
B) 40%
C) 33.33%
D) 60%
9. Which of the following is a unit of molarity?
A) mol/kg
B) g/L
C) mol/L
D) mol/m³
10. The law of definite proportions was proposed by:
A) John Dalton
B) Antoine Lavoisier
C) Joseph Proust
D) Both B and C
Structure of Atom (10 Questions)
11. The charge-to-mass ratio of an electron was determined by:
A) Rutherford
B) J.J. Thomson
C) Millikan
D) Bohr
12. The maximum number of electrons in the n=3 shell is:
A) 8
B) 18
C) 18
D) 32
13. The quantum number that specifies the shape of an orbital is:
A) Azimuthal quantum number
B) Principal quantum number
C) Magnetic quantum number
D) Spin quantum number
14. The atomic model that introduced the concept of quantized energy levels is:
A) Dalton’s model
B) Thomson’s model
C) Rutherford’s model
D) Bohr’s model
15. The wavelength of a photon is related to its energy by:
A) E = mc²
B) E = hc/λ
C) E = hν²
D) E = λ/hc
16. The Heisenberg uncertainty principle states that:
A) Electrons have a fixed orbit
B) Electrons behave only as particles
C) Position and momentum cannot be simultaneously measured with precision
D) Energy levels are continuous
17. The number of orbitals in the p subshell is:
A) 3
B) 1
C) 5
D) 7
18. The electronic configuration of sodium (atomic number 11) is:
A) 1s² 2s² 2p⁶ 3s²
B) 1s² 2s² 2p⁶ 3s¹
C) 1s² 2s² 2p⁵ 3s²
D) 1s² 2s² 2p⁷
19. The scientist who discovered the neutron is:
A) J.J. Thomson
B) Ernest Rutherford
C) James Chadwick
D) Niels Bohr
20. The Pauli exclusion principle states that:
A) Electrons occupy the lowest energy level
B) Electrons fill orbitals singly before pairing
C) Orbitals have specific shapes
D) No two electrons can have the same set of quantum numbers
Classification of Elements and Periodicity in Properties (10 Questions)
21. The modern periodic table is based on:
A) Atomic mass
B) Atomic number
C) Mass number
D) Neutron number
22. Elements in the same group have the same:
A) Number of valence electrons
B) Atomic radius
C) Electronegativity
D) Ionization energy
23. Which element has the highest electronegativity?
A) Sodium
B) Chlorine
C) Fluorine
D) Oxygen
24. The atomic radius generally decreases across a period from left to right due to:
A) Decrease in nuclear charge
B) Increase in electron shielding
C) Decrease in electron affinity
D) Increase in nuclear charge
25. Which group contains noble gases?
A) Group 1
B) Group 18
C) Group 17
D) Group 2
26. The element with atomic number 17 belongs to:
A) Halogens
B) Alkali metals
C) Alkaline earth metals
D) Noble gases
27. Ionization energy generally increases across a period because:
A) Atomic radius increases
B) Electron shielding increases
C) Nuclear charge increases
D) Valence electrons decrease
28. The element with the lowest ionization energy in Group 1 is:
A) Lithium
B) Caesium
C) Sodium
D) Potassium
29. The modern periodic law was proposed by:
A) Mendeleev
B) Dobereiner
C) Newlands
D) Moseley
30. Which block of the periodic table contains transition elements?
A) d-block
B) s-block
C) p-block
D) f-block
Chemical Bonding and Molecular Structure (10 Questions)
31. The type of bond formed between two non-metals is:
A) Ionic
B) Metallic
C) Covalent
D) Coordinate
32. The shape of a molecule with sp³ hybridization and no lone pairs is:
A) Linear
B) Tetrahedral
C) Trigonal planar
D) Bent
33. The bond order of N₂ is:
A) 3
B) 2
C) 1
D) 4
34. Which molecule exhibits hydrogen bonding?
A) CH₄
B) CCl₄
C) CO₂
D) H₂O
35. The VSEPR theory is used to predict:
A) Bond length
B) Bond energy
C) Molecular geometry
D) Bond order
36. The hybridization of carbon in CO₂ is:
A) sp³
B) sp
C) sp²
D) sp³d
37. Which of the following has a dipole moment?
A) NH₃
B) CO₂
C) BF₃
D) CCl₄
38. The bond angle in a water molecule is approximately:
A) 180°
B) 120°
C) 90°
D) 104.5°
39. A coordinate bond is also known as:
A) Ionic bond
B) Covalent bond
C) Dative bond
D) Metallic bond
40. The molecule with a linear shape is:
A) H₂O
B) CO₂
C) NH₃
D) CH₄
States of Matter (10 Questions)
41. The gas law that relates pressure and volume at constant temperature is:
A) Charles’ Law
B) Avogadro’s Law
C) Boyle’s Law
D) Gay-Lussac’s Law
42. The ideal gas equation is:
A) PV = nT
B) PV = nRT
C) P = nRT/V
D) PV = RT
43. The intermolecular forces in liquids are:
A) Weaker than in solids but stronger than in gases
B) Stronger than in solids
C) Equal to those in gases
D) Absent
44. The critical temperature of a gas is:
A) The temperature below which it behaves ideally
B) The temperature at which it freezes
C) The temperature at which it boils
D) The temperature above which it cannot be liquefied
45. The SI unit of pressure is:
A) Atmosphere
B) Torr
C) Pascal
D) Bar
46. The van der Waals equation corrects the ideal gas law for:
A) Temperature only
B) Volume and intermolecular forces
C) Pressure only
D) Number of moles
47. The process of conversion of a gas to a liquid is called:
A) Condensation
B) Sublimation
C) Evaporation
D) Fusion
48. The temperature at which a liquid’s vapor pressure equals atmospheric pressure is:
A) Melting point
B) Critical point
C) Boiling point
D) Freezing point
49. Which gas deviates most from ideal behavior?
A) He
B) Ne
C) Ar
D) NH₃
50. Dalton’s law of partial pressures applies to:
A) Single gases only
B) Mixture of non-reacting gases
C) Liquids
D) Solids
Thermodynamics (10 Questions)
51. The first law of thermodynamics is a statement of:
A) Conservation of energy
B) Conservation of mass
C) Entropy increase
D) Heat transfer
52. The SI unit of enthalpy is:
A) Joule per kelvin
B) Newton
C) Joule
D) Pascal
53. A process that occurs at constant pressure is called:
A) Isothermal
B) Isobaric
C) Isochoric
D) Adiabatic
54. The entropy of a system increases in:
A) Reversible processes only
B) Irreversible processes only
C) Adiabatic processes only
D) Spontaneous processes
55. The standard state of a substance is defined at:
A) 298 K and 1 bar
B) 273 K and 1 atm
C) 298 K and 1 atm
D) 273 K and 1 bar
56. The Gibbs free energy change (ΔG) determines:
A) Heat absorbed
B) Work done
C) Spontaneity of a reaction
D) Enthalpy change
57. A reaction is spontaneous if ΔG is:
A) Zero
B) Negative
C) Positive
D) Infinite
58. The heat capacity at constant volume is denoted as:
A) Cᵥ
B) Cₚ
C) Cₘ
D) Cₕ
59. Hess’s law is used to calculate:
A) Entropy change
B) Gibbs free energy
C) Work done
D) Enthalpy change
60. An adiabatic process involves:
A) Constant temperature
B) Constant pressure
C) No heat exchange
D) Constant volume
Equilibrium (10 Questions)
61. The equilibrium constant is denoted by:
A) Kₑ
B) Kc
C) Kₚ
D) Both B and C
62. Le Chatelier’s principle applies to:
A) Systems in equilibrium
B) Non-equilibrium systems
C) Irreversible reactions
D) Adiabatic processes
63. For the reaction N₂ + 3H₂ ⇌ 2NH₃, the equilibrium constant Kc is expressed in terms of:
A) Pressure
B) Volume
C) Concentration
D) Temperature
64. A strong acid completely dissociates in water, forming:
A) Weak conjugate base
B) Strong conjugate acid
C) Neutral solution
D) Weak conjugate acid
65. The pH of a neutral solution at 25°C is:
A) 0
B) 7
C) 14
D) 1
66. The ion product of water at 25°C is:
A) 10⁻¹⁴
B) 10⁻⁷
C) 10⁻¹²
D) 10⁻¹⁰
67. A buffer solution resists changes in:
A) Temperature
B) Volume
C) pH
D) Pressure
68. The solubility product (Ksp) is defined for:
A) Soluble salts
B) Sparingly soluble salts
C) Gases
D) Liquids
69. According to Le Chatelier’s principle, increasing pressure favors the reaction with:
A) More moles of products
B) Fewer moles of reactants
C) Equal moles on both sides
D) Fewer moles of products
70. The conjugate base of H₂SO₄ is:
A) HSO₄⁻
B) SO₄²⁻
C) H₃SO₄⁺
D) H₂SO₃
Redox Reactions (10 Questions)
71. In a redox reaction, the substance that loses electrons is:
A) Oxidizing agent
B) Catalyst
C) Reducing agent
D) Electrolyte
72. The oxidation number of oxygen in H₂O₂ is:
A) -2
B) -1
C) 0
D) +1
73. In the reaction 2Na + Cl₂ → 2NaCl, the oxidizing agent is:
A) Cl₂
B) Na
C) NaCl
D) None
74. The process of balancing a redox reaction in acidic medium involves:
A) Adding OH⁻ ions
B) Ignoring H⁺ ions
C) Adding electrons only
D) Adding H⁺ ions and H₂O
75. The oxidation number of sulfur in SO₄²⁻ is:
A) +2
B) +4
C) +6
D) +8
76. A galvanic cell produces:
A) Heat energy
B) Electrical energy
C) Mechanical energy
D) Chemical energy
77. In an electrochemical cell, the anode is the electrode where:
A) Oxidation occurs
B) Reduction occurs
C) Both occur
D) No reaction occurs
78. The standard hydrogen electrode has a potential of:
A) +1.0 V
B) -1.0 V
C) +0.5 V
D) 0.0 V
79. The reaction Zn + Cu²⁺ → Zn²⁺ + Cu is an example of:
A) Combination reaction
B) Decomposition reaction
C) Redox reaction
D) Precipitation reaction
80. The oxidation number of chlorine in Cl₂ is:
A) -1
B) 0
C) +1
D) +2
Hydrogen, s-Block, and p-Block Elements (10 Questions)
81. The most abundant isotope of hydrogen is:
A) Deuterium
B) Tritium
C) Protium
D) Hydronium
82. Hard water contains:
A) Ca²⁺ and Mg²⁺ ions
B) Na⁺ and K⁺ ions
C) Cl⁻ and SO₄²⁻ ions
D) H⁺ ions
83. The alkali metal with the highest melting point is:
A) Sodium
B) Lithium
C) Potassium
D) Caesium
84. The compound used as a fire extinguisher is:
A) NaCl
B) CaCO₃
C) Na₂SO₄
D) NaHCO₃
85. The most electronegative element in the p-block is:
A) Carbon
B) Nitrogen
C) Fluorine
D) Boron
86. The gas used in balloons is:
A) Helium
B) Hydrogen
C) Neon
D) Argon
87. The compound formed by the reaction of sodium with water is:
A) Na₂O
B) NaOH
C) Na₂CO₃
D) NaCl
88. The allotropic form of carbon used in lubricants is:
A) Diamond
B) Fullerene
C) Graphene
D) Graphite
89. The element used in the manufacture of fertilizers is:
A) Boron
B) Carbon
C) Nitrogen
D) Aluminium
90. The gas responsible for the greenhouse effect is:
A) CO₂
B) O₂
C) N₂
D) H₂
Organic Chemistry: Some Basic Principles (10 Questions)
91. The functional group in alcohols is:
A) -CHO
B) -COOH
C) -OH
D) -NH₂
92. The IUPAC name of CH₃CH₂OH is:
A) Methanol
B) Ethanol
C) Propanol
D) Butanol
93. The hybridization of carbon in ethene (C₂H₄) is:
A) sp²
B) sp³
C) sp
D) sp³d
94. The compound with the general formula CnH₂n is:
A) Alkane
B) Alkyne
C) Aromatic
D) Alkene
95. The process of breaking a compound into simpler substances using heat is called:
A) Sublimation
B) Distillation
C) Pyrolysis
D) Hydrolysis
96. The compound C₆H₆ is:
A) Cyclohexane
B) Benzene
C) Hexene
D) Hexyne
97. The functional group in aldehydes is:
A) -CHO
B) -COOH
C) -OH
D) -NH₂
98. Isomerism exhibited by compounds with the same molecular formula but different structural formulas is:
A) Stereoisomerism
B) Geometrical isomerism
C) Optical isomerism
D) Structural isomerism
99. The bond in ethyne (C₂H₂) is:
A) Single bond
B) Double bond
C) Triple bond
D) Ionic bond
100. The reaction of an alkene with Br₂ is an example of:
A) Substitution
B) Addition
C) Elimination
D) Rearrangement
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