1. What is the basic unit of matter?
A) Molecule
B) Atom
C) Compound
D) Element
Answer: B) Atom
2. Which of the following is a chemical change?
A) Ice melting
B) Sugar dissolving in water
C) Iron rusting
D) Water boiling
Answer: C) Iron rusting
3. What is the atomic number of an element?
A) Number of neutrons
B) Number of protons
C) Number of electrons
D) Total number of particles
Answer: B) Number of protons
4. Which of the following is a strong acid?
A) Acetic acid
B) Hydrochloric acid
C) Citric acid
D) Carbonic acid
Answer: B) Hydrochloric acid
5. What is the molar mass of water (H₂O)?
A) 16 g/mol
B) 18 g/mol
C) 20 g/mol
D) 22 g/mol
Answer: B) 18 g/mol
6. In the periodic table, elements are arranged by increasing:
A) Mass
B) Density
C) Atomic number
D) Volume
Answer: C) Atomic number
7. What type of bond involves the sharing of electron pairs between atoms?
A) Ionic bond
B) Covalent bond
C) Metallic bond
D) Hydrogen bond
Answer: B) Covalent bond
8. Which of the following elements is a noble gas?
A) Oxygen
B) Nitrogen
C) Argon
D) Hydrogen
Answer: C) Argon
9. What is the pH of a neutral solution at 25°C?
A) 0
B) 7
C) 14
D) 10
Answer: B) 7
10. Which of the following compounds is an alkane?
A) C₂H₄
B) C₃H₈
C) C₂H₂
D) C₃H₆
Answer: B) C₃H₈
11. What is the principle behind chromatography?
A) Boiling point
B) Density
C) Solubility
D) Diffusion
Answer: C) Solubility
12. Which of the following is a characteristic of metals?
A) Brittle
B) Poor conductors of heat
C) Malleable
D) Dull appearance
Answer: C) Malleable
13. Which reaction type involves the combination of two or more substances to form a single product?
A) Decomposition
B) Single replacement
C) Synthesis
D) Combustion
Answer: C) Synthesis
14. In a chemical equation, what do the coefficients represent?
A) The physical state of the reactants
B) The number of moles of a substance
C) The temperature of the reaction
D) The pressure of the system
Answer: B) The number of moles of a substance
15. What is the main product of the complete combustion of hydrocarbons?
A) Carbon monoxide
B) Carbon dioxide
C) Water
D) Both B and C
Answer: D) Both B and C
16. Which of the following is a property of acids?
A) Bitter taste
B) Slippery feel
C) Sour taste
D) Turns litmus blue
Answer: C) Sour taste
17. What is Avogadro’s number?
A) 6.022 × 10²³
B) 1.602 × 10⁻¹⁹
C) 3.14 × 10²
D) 9.81 × 10²
Answer: A) 6.022 × 10²³
18. What is the main characteristic of ionic compounds?
A) They have low melting points
B) They conduct electricity in solid form
C) They are formed from metals and nonmetals
D) They are typically gases at room temperature
Answer: C) They are formed from metals and nonmetals
19. Which gas is produced during the reaction of an acid with a metal?
A) Oxygen
B) Nitrogen
C) Hydrogen
D) Carbon dioxide
Answer: C) Hydrogen
20. In an endothermic reaction, energy is:
A) Released
B) Absorbed
C) Neither released nor absorbed
D) Converted to mass
Answer: B) Absorbed
21. What is the molecular formula for glucose?
A) C₆H₁₂O₆
B) C₁₂H₂₂O₁₁
C) C₆H₁₂O
D) C₆H₁₁O₆
Answer: A) C₆H₁₂O₆
22. Which of the following elements is most electronegative?
A) Sodium
B) Chlorine
C) Magnesium
D) Calcium
Answer: B) Chlorine
23. What is the main purpose of a buffer solution?
A) To change pH drastically
B) To maintain pH stability
C) To neutralize acids only
D) To increase acidity
Answer: B) To maintain pH stability
24. Which of the following is not a type of isomerism?
A) Structural isomerism
B) Geometric isomerism
C) Optical isomerism
D) Nuclear isomerism
Answer: D) Nuclear isomerism
25. What type of radiation is emitted during radioactive decay?
A) Alpha particles
B) Beta particles
C) Gamma rays
D) All of the above
Answer: D) All of the above
26. Which of the following compounds has a tetrahedral molecular geometry?
A) Water (H₂O)
B) Methane (CH₄)
C) Ammonia (NH₃)
D) Carbon dioxide (CO₂)
Answer: B) Methane (CH₄)
27. What is the main function of a catalyst in a chemical reaction?
A) To change the reaction products
B) To lower the activation energy
C) To increase the temperature
D) To absorb heat
Answer: B) To lower the activation energy
28. What is a polar molecule?
A) A molecule with an even distribution of charge
B) A molecule with a net dipole moment
C) A molecule that does not dissolve in water
D) A molecule that is highly reactive
Answer: B) A molecule with a net dipole moment
29. Which of the following elements has the highest atomic mass?
A) Hydrogen
B) Carbon
C) Oxygen
D) Uranium
Answer: D) Uranium
30. What type of intermolecular force is present in water?
A) Ionic bonds
B) Covalent bonds
C) Hydrogen bonds
D) Metallic bonds
Answer: C) Hydrogen bonds
31. Which law states that the volume of a gas is directly proportional to its temperature at constant pressure?
A) Boyle’s Law
B) Charles’s Law
C) Avogadro’s Law
D) Gay-Lussac’s Law
Answer: B) Charles’s Law
32. In a titration, what is the purpose of the indicator?
A) To measure the volume
B) To determine the endpoint of the reaction
C) To increase the reaction rate
D) To dilute the solution
Answer: B) To determine the endpoint of the reaction
33. Which of the following represents a saturated hydrocarbon?
A) C₂H₄
B) C₃H₆
C) C₅H₁₂
D) C₄H₈
Answer: C) C₅H₁₂
34. Which gas law relates pressure and volume at constant temperature?
A) Avogadro’s Law
B) Boyle’s Law
C) Charles’s Law
D) Ideal Gas Law
Answer: B) Boyle’s Law
35. What is the chemical formula for sulfuric acid?
A) H₂SO₄
B) H₂SO₃
C) HSO₄
D) H₃SO₄
Answer: A) H₂SO₄
36. Which of the following statements about metals is correct?
A) They are good insulators of heat
B) They are generally brittle
C) They conduct electricity
D) They have a dull appearance
Answer: C) They conduct electricity
37. In an experiment, the quantity of solute in a solution is increased. This process is known as:
A)
Dilution
B) Concentration
C) Saturation
D) Filtration
Answer: B) Concentration
38. The periodic trend that describes the ability of an atom to attract electrons is called:
A) Electronegativity
B) Ionization energy
C) Atomic radius
D) Electron affinity
Answer: A) Electronegativity
39. Which of the following is a property of bases?
A) Taste sour
B) React with metals to produce hydrogen gas
C) Feel slippery
D) Turn litmus paper red
Answer: C) Feel slippery
40. Which type of reaction involves the breakdown of a compound into simpler substances?
A) Synthesis
B) Decomposition
C) Single replacement
D) Double replacement
Answer: B) Decomposition
41. The term “stoichiometry” refers to:
A) The study of energy changes in reactions
B) The calculation of reactants and products in chemical reactions
C) The behavior of gases
D) The arrangement of electrons in atoms
Answer: B) The calculation of reactants and products in chemical reactions
42. What is the primary function of a reagent in a chemical reaction?
A) To act as a catalyst
B) To change color
C) To react and form products
D) To dilute the solution
Answer: C) To react and form products
43. Which of the following compounds is an example of a nonpolar molecule?
A) H₂O
B) NH₃
C) CO₂
D) CH₃OH
Answer: C) CO₂
44. In which state of matter do particles have the least energy?
A) Solid
B) Liquid
C) Gas
D) Plasma
Answer: A) Solid
45. Which type of mixture has a uniform composition throughout?
A) Heterogeneous mixture
B) Homogeneous mixture
C) Colloid
D) Suspension
Answer: B) Homogeneous mixture
46. Which element is commonly used in the manufacture of glass?
A) Silicon
B) Calcium
C) Iron
D) Sodium
Answer: A) Silicon
47. The energy required to remove an electron from an atom is called:
A) Electronegativity
B) Ionization energy
C) Electron affinity
D) Atomic radius
Answer: B) Ionization energy
48. In which type of bond do electrons transfer from one atom to another?
A) Covalent bond
B) Ionic bond
C) Metallic bond
D) Hydrogen bond
Answer: B) Ionic bond
49. Which gas law states that the pressure of a gas is inversely proportional to its volume at constant temperature?
A) Charles’s Law
B) Boyle’s Law
C) Gay-Lussac’s Law
D) Ideal Gas Law
Answer: B) Boyle’s Law
50. Which of the following best describes a solution?
A) A mixture of solids
B) A homogeneous mixture of two or more substances
C) A substance with a fixed composition
D) A heterogeneous mixture of liquids
Answer: B) A homogeneous mixture of two or more substances