Practice 100 Chemistry Basics MCQs with answers covering atoms, elements, compounds, reactions, acids, bases, and the periodic table. Ideal for students, exams, and competitive test preparation.
Chemistry Basics form the foundation for understanding matter, its composition, properties, and the changes it undergoes in everyday life. A strong grasp of fundamental concepts such as atoms, molecules, elements, compounds, chemical reactions, acids, bases, and the periodic table is essential for students and exam aspirants. This article presents 100 carefully designed Chemistry Basics MCQs with answers, aimed at strengthening core concepts, supporting quick revision, and improving exam readiness. These basic chemistry multiple choice questions are ideal for school exams, competitive tests, and general science learning.
Below are 100 MCQs on Chemistry Basics, written in clear and correct English, suitable for school exams, competitive exams, and general science practice.
⚗️ Chemistry Basics – 100 Multiple Choice Questions (MCQs) with Answers
1. Chemistry is the study of:
A. Living organisms
B. Matter and its changes
C. Energy only
D. Motion
Answer: B
2. Matter is anything that has:
A. Energy
B. Force
C. Mass and occupies space
D. Shape only
Answer: C
3. Which of the following is a physical change?
A. Burning of paper
B. Rusting of iron
C. Melting of ice
D. Cooking of food
Answer: C
4. Which of the following is a chemical change?
A. Freezing water
B. Dissolving sugar
C. Burning coal
D. Cutting paper
Answer: C
5. The smallest unit of matter is:
A. Molecule
B. Atom
C. Cell
D. Compound
Answer: B
6. Atoms combine to form:
A. Elements
B. Compounds
C. Molecules
D. Mixtures
Answer: C
7. An element is a substance that:
A. Can be broken down easily
B. Contains two or more elements
C. Cannot be broken into simpler substances
D. Is always liquid
Answer: C
8. Which of the following is an element?
A. Water
B. Air
C. Oxygen
D. Salt
Answer: C
9. A compound is formed by:
A. Physical mixing
B. Chemical combination
C. Mechanical separation
D. Heating only
Answer: B
10. Which of the following is a compound?
A. Oxygen
B. Hydrogen
C. Carbon
D. Water
Answer: D
11. A mixture can be separated by:
A. Chemical methods only
B. Physical methods
C. Nuclear methods
D. Atomic methods
Answer: B
12. Air is an example of:
A. Element
B. Compound
C. Homogeneous mixture
D. Heterogeneous mixture
Answer: C
13. Which of the following is a heterogeneous mixture?
A. Salt solution
B. Sugar solution
C. Air
D. Sand and water
Answer: D
14. The SI unit of mass is:
A. Gram
B. Kilogram
C. Pound
D. Tonne
Answer: B
15. The SI unit of temperature is:
A. Celsius
B. Fahrenheit
C. Kelvin
D. Joule
Answer: C
16. Density is defined as:
A. Mass × volume
B. Volume ÷ mass
C. Mass ÷ volume
D. Mass + volume
Answer: C
17. Which state of matter has a fixed shape and volume?
A. Solid
B. Liquid
C. Gas
D. Plasma
Answer: A
18. Which state of matter has no fixed shape but fixed volume?
A. Solid
B. Liquid
C. Gas
D. Plasma
Answer: B
19. Which state of matter has neither fixed shape nor volume?
A. Solid
B. Liquid
C. Gas
D. Ice
Answer: C
20. The change from solid to liquid is called:
A. Freezing
B. Condensation
C. Melting
D. Evaporation
Answer: C
21. The change from liquid to gas is called:
A. Melting
B. Freezing
C. Condensation
D. Evaporation
Answer: D
22. The change from gas to liquid is called:
A. Evaporation
B. Condensation
C. Sublimation
D. Freezing
Answer: B
23. Sublimation is the change from:
A. Solid to gas
B. Gas to solid
C. Liquid to gas
D. Liquid to solid
Answer: A
24. Which substance shows sublimation?
A. Ice
B. Water
C. Naphthalene
D. Salt
Answer: C
25. Atomic number represents the number of:
A. Neutrons
B. Electrons + protons
C. Protons
D. Nucleons
Answer: C
26. Mass number is the total number of:
A. Protons
B. Neutrons
C. Protons + neutrons
D. Electrons
Answer: C
27. The negatively charged particle is:
A. Proton
B. Neutron
C. Electron
D. Nucleus
Answer: C
28. The positively charged particle is:
A. Electron
B. Neutron
C. Proton
D. Atom
Answer: C
29. Neutrons have:
A. Positive charge
B. Negative charge
C. No charge
D. Double charge
Answer: C
30. The nucleus of an atom contains:
A. Protons and electrons
B. Neutrons and electrons
C. Protons and neutrons
D. Only electrons
Answer: C
31. Isotopes have the same:
A. Mass number
B. Atomic number
C. Number of neutrons
D. Chemical properties only
Answer: B
32. Which of the following is an isotope of hydrogen?
A. Oxygen
B. Carbon
C. Deuterium
D. Helium
Answer: C
33. Valency is the:
A. Atomic mass
B. Combining capacity
C. Number of neutrons
D. Atomic size
Answer: B
34. The chemical symbol for sodium is:
A. Na
B. So
C. S
D. No
Answer: A
35. The chemical symbol for potassium is:
A. P
B. K
C. Pt
D. Po
Answer: B
36. The periodic table was developed by:
A. Dalton
B. Bohr
C. Mendeleev
D. Rutherford
Answer: C
37. Modern periodic table is based on:
A. Atomic mass
B. Atomic volume
C. Atomic number
D. Density
Answer: C
38. Elements in the same group have the same:
A. Atomic mass
B. Number of shells
C. Valence electrons
D. Atomic size
Answer: C
39. Elements in the same period have the same:
A. Valency
B. Number of shells
C. Atomic number
D. Chemical properties
Answer: B
40. Noble gases are found in:
A. Group 1
B. Group 2
C. Group 17
D. Group 18
Answer: D
41. Which gas is most abundant in air?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Hydrogen
Answer: C
42. Which gas supports combustion?
A. Nitrogen
B. Oxygen
C. Carbon dioxide
D. Hydrogen
Answer: B
43. The chemical formula of water is:
A. HO
B. H₂O
C. H₂O₂
D. OH₂
Answer: B
44. Acids turn blue litmus:
A. Red
B. Green
C. Yellow
D. Blue
Answer: A
45. Bases turn red litmus:
A. Blue
B. Green
C. Yellow
D. Red
Answer: A
46. Which of the following is an acid?
A. NaOH
B. KOH
C. HCl
D. Ca(OH)₂
Answer: C
47. Which of the following is a base?
A. H₂SO₄
B. HNO₃
C. NaOH
D. HCl
Answer: C
48. The pH value of a neutral solution is:
A. 0
B. 5
C. 7
D. 14
Answer: C
49. A solution with pH less than 7 is:
A. Neutral
B. Basic
C. Acidic
D. Salty
Answer: C
50. A solution with pH greater than 7 is:
A. Acidic
B. Neutral
C. Basic
D. Salty
Answer: C
51. Common salt is chemically:
A. Sodium chloride
B. Sodium carbonate
C. Calcium chloride
D. Potassium chloride
Answer: A
52. Baking soda is:
A. NaCl
B. Na₂CO₃
C. NaHCO₃
D. CaCO₃
Answer: C
53. Washing soda is:
A. NaHCO₃
B. Na₂CO₃
C. CaCO₃
D. K₂CO₃
Answer: B
54. Lime water contains:
A. Calcium oxide
B. Calcium hydroxide
C. Calcium carbonate
D. Sodium hydroxide
Answer: B
55. Slaked lime is:
A. CaO
B. CaCO₃
C. Ca(OH)₂
D. NaOH
Answer: C
56. Rusting of iron requires:
A. Water only
B. Oxygen only
C. Water and oxygen
D. Carbon dioxide only
Answer: C
57. Rust is chemically:
A. Iron oxide
B. Iron hydroxide
C. Iron carbonate
D. Iron chloride
Answer: A
58. Corrosion is:
A. Physical process
B. Chemical process
C. Nuclear process
D. Mechanical process
Answer: B
59. Galvanization prevents rusting by coating iron with:
A. Copper
B. Zinc
C. Silver
D. Gold
Answer: B
60. Alloys are:
A. Pure metals
B. Pure non-metals
C. Mixtures of metals
D. Compounds only
Answer: C
61. Steel is an alloy of:
A. Iron and copper
B. Iron and zinc
C. Iron and carbon
D. Iron and aluminum
Answer: C
62. Brass is an alloy of:
A. Copper and iron
B. Copper and zinc
C. Iron and zinc
D. Aluminum and copper
Answer: B
63. Bronze is an alloy of:
A. Copper and tin
B. Copper and zinc
C. Iron and carbon
D. Aluminum and iron
Answer: A
64. Metals are generally:
A. Brittle
B. Poor conductors
C. Malleable and ductile
D. Transparent
Answer: C
65. Non-metals are generally:
A. Ductile
B. Good conductors
C. Brittle
D. Malleable
Answer: C
66. Which metal is liquid at room temperature?
A. Sodium
B. Mercury
C. Iron
D. Aluminum
Answer: B
67. Which non-metal is liquid at room temperature?
A. Sulfur
B. Phosphorus
C. Bromine
D. Chlorine
Answer: C
68. The most reactive metal is:
A. Iron
B. Copper
C. Potassium
D. Gold
Answer: C
69. The least reactive metal is:
A. Iron
B. Zinc
C. Copper
D. Gold
Answer: D
70. Metals lose electrons to form:
A. Anions
B. Neutrals
C. Cations
D. Molecules
Answer: C
71. Non-metals gain electrons to form:
A. Cations
B. Anions
C. Neutrals
D. Ions
Answer: B
72. Oxidation involves:
A. Gain of electrons
B. Loss of electrons
C. Gain of neutrons
D. Loss of protons
Answer: B
73. Reduction involves:
A. Loss of electrons
B. Gain of electrons
C. Loss of protons
D. Gain of neutrons
Answer: B
74. Oxidation and reduction occur:
A. Separately
B. Together
C. Alternately
D. Randomly
Answer: B
75. The substance that gets oxidized is called:
A. Oxidizing agent
B. Reducing agent
C. Catalyst
D. Acid
Answer: B
76. A catalyst:
A. Takes part permanently
B. Is consumed
C. Changes rate without being consumed
D. Stops reaction
Answer: C
77. Endothermic reactions:
A. Release heat
B. Absorb heat
C. Do not involve heat
D. Produce light
Answer: B
78. Exothermic reactions:
A. Absorb heat
B. Release heat
C. Do not involve energy
D. Absorb light
Answer: B
79. Chemical equations must be:
A. Unbalanced
B. Balanced
C. Incomplete
D. Random
Answer: B
80. Law of conservation of mass was proposed by:
A. Dalton
B. Newton
C. Lavoisier
D. Boyle
Answer: C
81. The mole is a unit of:
A. Mass
B. Volume
C. Amount of substance
D. Density
Answer: C
82. Avogadro’s number is:
A. 6.02 × 10²²
B. 6.02 × 10²³
C. 6.02 × 10²¹
D. 6.02 × 10²⁴
Answer: B
83. The molar mass of water is:
A. 16 g/mol
B. 17 g/mol
C. 18 g/mol
D. 20 g/mol
Answer: C
84. Solutions are:
A. Pure substances
B. Mixtures
C. Elements
D. Compounds only
Answer: B
85. Solvent is the substance that:
A. Dissolves
B. Is dissolved
C. Reacts
D. Evaporates
Answer: A
86. Solute is the substance that:
A. Dissolves
B. Is dissolved
C. Does not dissolve
D. Evaporates
Answer: B
87. A saturated solution contains:
A. No solute
B. Maximum solute
C. Less solute
D. No solvent
Answer: B
88. Crystallization is used to:
A. Mix substances
B. Purify solids
C. Heat solutions
D. Form gases
Answer: B
89. Distillation is used to separate:
A. Solids
B. Two solids
C. Liquids with different boiling points
D. Gases only
Answer: C
90. Filtration is used to separate:
A. Two liquids
B. Solid from liquid
C. Gases
D. Solutions
Answer: B
91. Chromatography is used to separate:
A. Metals
B. Insoluble solids
C. Colored substances
D. Gases only
Answer: C
92. Evaporation helps in separating:
A. Solids from solids
B. Liquids from liquids
C. Soluble solids from liquids
D. Gases
Answer: C
93. The boiling point of water is:
A. 0°C
B. 50°C
C. 100°C
D. 150°C
Answer: C
94. Freezing point of water is:
A. 100°C
B. 50°C
C. 0°C
D. –10°C
Answer: C
95. Pure water has pH:
A. 0
B. 5
C. 7
D. 14
Answer: C
96. The universal solvent is:
A. Alcohol
B. Water
C. Acetone
D. Ether
Answer: B
97. Chemistry helps us understand:
A. Life processes
B. Matter and reactions
C. Motion only
D. Energy only
Answer: B
98. The study of carbon compounds is called:
A. Inorganic chemistry
B. Physical chemistry
C. Organic chemistry
D. Analytical chemistry
Answer: C
99. Inorganic chemistry deals with:
A. Living organisms
B. Carbon compounds only
C. Non-carbon compounds
D. DNA
Answer: C
100. Chemistry plays an important role in:
A. Medicine
B. Industry
C. Environment
D. All of these
Answer: D
