1. Question 1 of 100

   Avogadro's number is approximately:

   A 6.022 × 10²³ B 3.14 × 10²³ C 6.022 × 10⁴ D 1.6 × 10⁻¹⁹
2. Question 2 of 100

   In the same reaction (Zn + CuSO₄ → ZnSO₄ + Cu), the copper ion (Cu²⁺) is:

   A Reduced, gaining electrons to form Cu B Oxidized C Unchanged D Acting as a catalyst
3. Question 3 of 100

   The substance that gets oxidized and donates electrons to another substance is called the:

   A Oxidizing agent B Reducing agent C Catalyst D Neutral substance
4. Question 4 of 100

   A substance that speeds up a chemical reaction without being consumed is called a:

   A Reactant B Product C Catalyst D Solvent
5. Question 5 of 100

   The reaction Zn + CuSO₄ → ZnSO₄ + Cu is an example of a:

   A Decomposition reaction B Displacement reaction C Combination reaction D Combustion reaction
6. Question 6 of 100

   Given CaCO₃ → CaO + CO₂, how many moles of CO₂ are produced from 5 moles of CaCO₃ decomposing completely?

   A 1 mole B 10 moles C 2.5 moles D 5 moles
7. Question 7 of 100

   The new substances formed as a result of a chemical reaction are called:

   A Reactants B Elements C Products D Mixtures
8. Question 8 of 100

   The mass of one mole of oxygen gas (O₂, O=16) is:

   A 16 g B 8 g C 64 g D 32 g
9. Question 9 of 100

   Which of the following correctly relates moles, mass, and molar mass?

   A Moles = Mass × Molar mass B Moles = Molar mass / Mass C Moles = Mass / Molar mass D Moles = Mass + Molar mass
10. Question 10 of 100

    The reaction between an acid and a base that produces a salt and water is called:

    A Oxidation B Decomposition C Combustion D Neutralization
11. Question 11 of 100

    Which symbol in a chemical equation is used to indicate a substance is in gaseous state?

    A (s) B (l) C (g) D (aq)
12. Question 12 of 100

    A neutralization reaction occurs between:

    A An acid and a base B Two acids C Two metals D An acid and a metal only
13. Question 13 of 100

    A solution with a pH greater than 7 is:

    A Acidic B Neutral C Basic (alkaline) D Always water
14. Question 14 of 100

    Melting of ice into water is an example of a:

    A Chemical change B Physical change C Combustion reaction D Decomposition reaction
15. Question 15 of 100

    A chemical reaction is a process in which:

    A New substances with different properties are formed from reactants B Only the physical state of a substance changes C No new substance is formed D Only the shape of a substance changes
16. Question 16 of 100

    In the reaction 2H₂ + O₂ → 2H₂O, how many grams of water are produced from 4 moles of hydrogen gas reacting completely (molar mass of H₂O = 18 g/mol)?

    A 18 g B 72 g C 36 g D 144 g
17. Question 17 of 100

    Which of the following is a physical change (not a chemical reaction)?

    A Cooking an egg B Burning paper C Rusting of a nail D Cutting a piece of paper into smaller pieces
18. Question 18 of 100

    In the reaction N₂ + 3H₂ → 2NH₃, how many moles of NH₃ are produced from 2 moles of N₂ (with excess H₂)?

    A 2 moles B 3 moles C 4 moles D 6 moles
19. Question 19 of 100

    Which type of reaction generally requires energy input (such as heat, light, or electricity) to proceed?

    A Decomposition reaction B Combination reaction C Neutralization reaction D Precipitation reaction
20. Question 20 of 100

    Photosynthesis (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂) is an example of a:

    A Decomposition reaction B Displacement reaction C Combustion reaction D Combination (synthesis) reaction
21. Question 21 of 100

    The reaction CaCO₃ → CaO + CO₂ (on heating) is an example of a:

    A Decomposition reaction B Combination reaction C Displacement reaction D Neutralization reaction
22. Question 22 of 100

    The general product of a typical acid-base neutralization reaction is:

    A Only a gas B A salt and water C Only heat D A precipitate always
23. Question 23 of 100

    Photosynthesis in plants is an example of a:

    A Chemical reaction that produces glucose and oxygen B Physical change C Decomposition of water D No change at all
24. Question 24 of 100

    The oxidation state of an element in its free (uncombined) state is always:

    A +1 B -1 D +2
25. Question 25 of 100

    The general equation for neutralization is:

    A Acid + Base → Salt + Water B Acid + Salt → Base + Water C Base + Water → Acid + Salt D Salt + Water → Acid + Base
26. Question 26 of 100

    Oxidation is defined as the process in which a substance:

    A Gains electrons B Loses protons C Loses electrons D Gains protons
27. Question 27 of 100

    To balance CH₄ + O₂ → CO₂ + H₂O, the correct balanced equation is:

    A CH₄ + 2O₂ → CO₂ + 2H₂O B CH₄ + O₂ → CO₂ + H₂O C CH₄ + 2O₂ → 2CO₂ + H₂O D 2CH₄ + O₂ → CO₂ + H₂O
28. Question 28 of 100

    In the compound water (H₂O), the oxidation state of hydrogen is typically:

    A -1 B 0 C +2 D +1
29. Question 29 of 100

    Red litmus paper turns blue in the presence of a(n):

    A Base B Acid C Neutral substance D Metal
30. Question 30 of 100

    In the reaction CaCO₃ → CaO + CO₂, how many grams of CaO are produced from 50 g of CaCO₃ (molar mass CaCO₃ = 100 g/mol, CaO = 56 g/mol)?

    A 28 g B 14 g C 50 g D 56 g
31. Question 31 of 100

    To balance the equation N₂ + H₂ → NH₃, the correct coefficients are:

    A N₂ + H₂ → 2NH₃ B 2N₂ + H₂ → NH₃ C N₂ + 3H₂ → NH₃ D N₂ + 3H₂ → 2NH₃
32. Question 32 of 100

    Rusting of iron is a redox reaction in which iron is:

    A Reduced by oxygen B Oxidized by oxygen in the presence of moisture C Unaffected by oxygen D Acting as an oxidizing agent
33. Question 33 of 100

    In the reaction 2H₂ + O₂ → 2H₂O, how many moles of water are produced from 6 moles of hydrogen gas (with excess oxygen)?

    A 3 moles B 9 moles C 12 moles D 6 moles
34. Question 34 of 100

    Electrolysis of water into hydrogen and oxygen gas is an example of a:

    A Combination reaction B Decomposition reaction C Displacement reaction D Combustion reaction
35. Question 35 of 100

    If 10 g of a reactant produces 7.5 g of product in a reaction with a theoretical maximum yield of 10 g of product, the percentage yield of the reaction is:

    A 50% B 65% C 100% D 75%
36. Question 36 of 100

    In the unbalanced equation H₂ + O₂ → H₂O, the correctly balanced form is:

    A H₂ + O₂ → H₂O B H₂ + 2O₂ → H₂O C 2H₂ + O₂ → 2H₂O D 2H₂ + 2O₂ → 2H₂O
37. Question 37 of 100

    The substance that gets reduced and accepts electrons from another substance is called the:

    A Reducing agent B Catalyst C Oxidizing agent D Solvent
38. Question 38 of 100

    The atomic mass of an element is usually expressed in:

    A Grams B Litres C Moles D Atomic mass units (amu)
39. Question 39 of 100

    In a balanced chemical equation, the coefficients represent:

    A The mass of each substance only B The relative number of moles (or particles) of each substance C The temperature of the reaction D The color of each substance
40. Question 40 of 100

    A reaction in which two or more substances combine to form a single new substance is called a:

    A Decomposition reaction B Displacement reaction C Double displacement reaction D Combination (synthesis) reaction
41. Question 41 of 100

    In the reaction 2Mg + O₂ → 2MgO, 4 moles of Mg are reacted with 3 moles of O₂. Since only 2 moles of O₂ are needed for 4 moles of Mg, the limiting reagent is:

    A Mg B O₂ C Both react completely with none left over D Neither reactant is limiting
42. Question 42 of 100

    In a displacement (single replacement) reaction, a more reactive element:

    A Combines with another element only B Displaces a less reactive element from its compound C Breaks down into simpler parts D Does not react at all
43. Question 43 of 100

    A reaction has a theoretical yield of 50 g of product, but the actual yield obtained is 40 g. The percentage yield is:

    A 60% B 70% C 90% D 80%
44. Question 44 of 100

    Which of the following is an example of an endothermic reaction?

    A Combustion of wood B Rusting of iron C Photosynthesis in plants D An explosion
45. Question 45 of 100

    A precipitation reaction occurs when two soluble solutions react to form:

    A A gas B Only heat C A new soluble solution with no solid D An insoluble solid (precipitate)
46. Question 46 of 100

    The symbol (aq) in a chemical equation indicates that a substance is:

    A A solid B A gas C In its pure liquid form D Dissolved in water (aqueous solution)
47. Question 47 of 100

    Blue litmus paper turns red in the presence of a(n):

    A Base B Neutral substance C Salt D Acid
48. Question 48 of 100

    The substances that react together in a chemical reaction are called:

    A Products B Reactants C Catalysts D Solvents
49. Question 49 of 100

    Burning of wood is an example of a:

    A Physical change B Reversible change only C Chemical change D No reaction
50. Question 50 of 100

    In most compounds, the oxidation state of oxygen is typically:

    A -2 B +2 D +1
51. Question 51 of 100

    Balancing chemical equations is necessary mainly to satisfy the:

    A Law of definite proportions B Law of conservation of mass C Law of multiple proportions D Avogadro's law
52. Question 52 of 100

    A reaction in which a single compound breaks down into two or more simpler substances is called a:

    A Decomposition reaction B Combination reaction C Combustion reaction D Precipitation reaction
53. Question 53 of 100

    Digestion of food in our body involves mainly:

    A Physical changes only B Chemical reactions that break down food into simpler substances C No reactions D Nuclear reactions
54. Question 54 of 100

    A reaction that proceeds rapidly, often with a flame, and produces mostly heat and light is called a:

    A Decomposition reaction B Double displacement reaction C Combustion reaction D Reduction reaction
55. Question 55 of 100

    In a chemical equation, the arrow (→) between reactants and products means:

    A Produces / yields B Equals C Is divided by D Is greater than
56. Question 56 of 100

    The number of moles of NaCl present in 117 g of NaCl (molar mass = 58.5 g/mol) is:

    A 1 mole B 2 moles C 3 moles D 0.5 mole
57. Question 57 of 100

    An atom consists mainly of:

    A Protons and neutrons in the nucleus, with electrons orbiting around it B Only protons C Only electrons D Only neutrons
58. Question 58 of 100

    In a double displacement reaction, two compounds react by:

    A Breaking into elements B Combining into a single compound C Exchanging their ions to form two new compounds D Releasing only heat
59. Question 59 of 100

    In the equation 2Mg + O₂ → 2MgO, how many moles of oxygen gas are needed to react completely with 4 moles of magnesium?

    A 1 mole B 4 moles C 2 moles D 8 moles
60. Question 60 of 100

    A combustion reaction typically involves a substance reacting rapidly with:

    A Water B Nitrogen C Carbon dioxide only D Oxygen, producing heat and light
61. Question 61 of 100

    A redox reaction always involves:

    A Both oxidation and reduction occurring together B Only oxidation C Only reduction D Neither oxidation nor reduction
62. Question 62 of 100

    An exothermic reaction is one that:

    A Absorbs heat from the surroundings B Produces no heat change C Only occurs in gases D Releases heat to the surroundings
63. Question 63 of 100

    In the reaction 2Al + 3Cl₂ → 2AlCl₃, if 4 moles of Al react completely with excess Cl₂, the moles of AlCl₃ produced are:

    A 2 moles B 6 moles C 4 moles D 8 moles
64. Question 64 of 100

    In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, zinc is:

    A Reduced B Unchanged C Acting as a catalyst D Oxidized, losing electrons to copper ions
65. Question 65 of 100

    Which of the following is an example of an exothermic reaction?

    A Melting of ice B Burning of fuel C Photosynthesis D Evaporation of water
66. Question 66 of 100

    Stoichiometry is the branch of chemistry that deals with:

    A The quantitative relationships between reactants and products in a chemical reaction B The color changes in reactions C The speed of a reaction only D The physical states of reactants
67. Question 67 of 100

    Reduction is defined as the process in which a substance:

    A Loses electrons B Loses protons C Gains protons D Gains electrons
68. Question 68 of 100

    The law of conservation of mass states that in a chemical reaction:

    A Mass can be created B Mass can be destroyed C Mass always increases D Mass is neither created nor destroyed, only transformed
69. Question 69 of 100

    What is the molarity of a solution containing 2 moles of solute dissolved in 4 litres of solution?

    A 2 M B 4 M C 0.5 M D 8 M
70. Question 70 of 100

    When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), the products are:

    A NaH and ClO B NaCl and H₂O C Na₂O and HCl D NaOH and HCl
71. Question 71 of 100

    If a reaction has excess of one reactant and a limited amount of another, the amount of product formed is determined by the:

    A Excess reactant B Limiting reactant C Catalyst D Solvent used
72. Question 72 of 100

    Rusting of iron is an example of a:

    A Chemical change B Physical change C Nuclear change D No change
73. Question 73 of 100

    A base is a substance that, when dissolved in water, produces:

    A Hydrogen ions (H⁺) B Only acids C Only metals D Hydroxide ions (OH⁻)
74. Question 74 of 100

    Litmus paper is commonly used to test whether a substance is:

    A A metal or non-metal B Solid or liquid C Acidic or basic D A compound or an element
75. Question 75 of 100

    The reaction 2H₂ + O₂ → 2H₂O is an example of a:

    A Decomposition reaction B Displacement reaction C Combination reaction D Double displacement reaction
76. Question 76 of 100

    The molar mass of water (H₂O) is approximately:

    A 16 g/mol B 20 g/mol C 34 g/mol D 18 g/mol
77. Question 77 of 100

    Which of the following is a sign that a chemical reaction has occurred?

    A Change in shape only B Melting of ice C Dissolving sugar in water D Formation of a gas, a precipitate, or a color change
78. Question 78 of 100

    How many moles of solute are present in 2 litres of a 3 M solution?

    A 1.5 moles B 3 moles C 5 moles D 6 moles
79. Question 79 of 100

    Common table salt (NaCl) is formed from the neutralization of:

    A Sulfuric acid and potassium hydroxide B Hydrochloric acid and sodium hydroxide C Nitric acid and calcium hydroxide D Carbonic acid and ammonia
80. Question 80 of 100

    The molecular formula of a compound shows:

    A Only the elements present, not their ratio B Only the empirical ratio C Only the mass of the compound D The actual number of atoms of each element in one molecule of the compound
81. Question 81 of 100

    Balancing a chemical equation involves adjusting the:

    A Subscripts of the formulas B Coefficients in front of the formulas C Charges on the ions only D Names of the compounds
82. Question 82 of 100

    Knowing the limiting reagent in a reaction allows you to correctly calculate the:

    A Color of the product B Theoretical (maximum possible) yield of product C Temperature of the reaction only D Catalyst needed
83. Question 83 of 100

    A sample of 8 g of hydrogen gas (H₂, molar mass = 2 g/mol) reacts completely with oxygen according to 2H₂ + O₂ → 2H₂O. The number of moles of oxygen required is:

    A 1 mole B 4 moles C 2 moles D 8 moles
84. Question 84 of 100

    A solution with a pH less than 7 is:

    A Basic (alkaline) B Acidic C Neutral D Always a salt
85. Question 85 of 100

    In a balanced equation, stoichiometric coefficients represent the mole ratio of:

    A Only reactants B Reactants and products involved in the reaction C Only products D Only catalysts
86. Question 86 of 100

    An acid is a substance that, when dissolved in water, produces:

    A Hydroxide ions (OH⁻) B Only salts C Hydrogen ions (H⁺) D Only gases
87. Question 87 of 100

    The molecular mass of carbon dioxide (CO₂) is approximately (C=12, O=16):

    A 44 g/mol B 28 g/mol C 32 g/mol D 60 g/mol
88. Question 88 of 100

    A reaction in which a metal displaces a less reactive metal from its compound is an example of a:

    A Non-redox reaction B Redox reaction C Neutralization reaction D Decomposition reaction only
89. Question 89 of 100

    The number of moles in 36 g of water (molar mass = 18 g/mol) is:

    A 1 mole B 2 moles C 3 moles D 0.5 mole
90. Question 90 of 100

    An endothermic reaction is one that:

    A Absorbs heat from the surroundings B Releases heat C Produces light only D Never occurs naturally
91. Question 91 of 100

    What volume (in litres) of a 2 M solution is needed to obtain 4 moles of solute?

    A 2 L B 0.5 L C 1 L D 8 L
92. Question 92 of 100

    A balanced chemical equation shows that:

    A The number of molecules is always equal on both sides B Only the reactants are shown C The number of atoms of each element is the same on both sides D Energy is never involved
93. Question 93 of 100

    The limiting reagent in a chemical reaction is the reactant that:

    A Is completely consumed first, limiting the amount of product formed B Is present in excess C Does not react at all D Acts as a catalyst
94. Question 94 of 100

    In the reaction 2Al + 3Cl₂ → 2AlCl₃, how many moles of Cl₂ are needed to completely react with 6 moles of Al?

    A 6 moles B 9 moles C 12 moles D 3 moles
95. Question 95 of 100

    The molar mass of a substance is defined as the mass of:

    A One atom of the substance B One molecule only C One mole of the substance, in grams D One litre of the substance
96. Question 96 of 100

    At standard temperature and pressure (STP), one mole of any gas occupies approximately:

    A 1 litre B 100 litres C 22.4 litres D 6.022 litres
97. Question 97 of 100

    In the reaction N₂ + 3H₂ → 2NH₃, if the theoretical yield of NH₃ is 34 g but only 25.5 g is actually obtained, the percentage yield is:

    A 50% B 65% C 75% D 85%
98. Question 98 of 100

    The pH scale ranges from 0 to 14, where a pH of 7 indicates a:

    A Neutral solution B Strongly acidic solution C Strongly basic solution D Undefined solution
99. Question 99 of 100

    To balance Fe + O₂ → Fe₂O₃, the correct balanced equation is:

    A 4Fe + 3O₂ → 2Fe₂O₃ B Fe + O₂ → Fe₂O₃ C 2Fe + O₂ → Fe₂O₃ D Fe + 3O₂ → 2Fe₂O₃
100. Question 100 of 100

     One mole of any substance contains how many particles (atoms, molecules, or ions)?

     A 10²³ B 6.022 × 10²³ C 1000 D 22.4

You can practise as a guest, but sign in to save your score and track your progress.