Chemistry is a fascinating subject that forms the foundation of many scientific advancements. To truly understand its principles, mastering some basic concepts is essential. Topics like atomic structure, chemical bonding, and the periodic table provide the building blocks for further learning. One of the most effective ways to test and strengthen your knowledge is through some basic concepts of chemistry MCQ practice. These multiple-choice questions not only help you retain important information but also improve your problem-solving skills. In this article, you’ll explore essential chemistry concepts and discover how MCQs can make learning more engaging and effective.
Some Basic Concepts of Chemistry MCQ
- Who proposed the atomic theory in 1808?
- a) Dalton
b) Rutherford
c) Bohr
d) Einstein
Answer: a) Dalton
2. What is the charge of an electron?
a) Positive
b) Negative
c) Neutral
d) Variable
Answer: b) Negative
3. What is the mass number of an element with 6 protons and 7 neutrons?
a) 6
b) 7
c) 13
d) 14
Answer: c) 13
4. Which particle determines the identity of an element?
a) Proton
b) Neutron
c) Electron
d) Nucleus
Answer: a) Proton
5. The atomic number of an element is equal to the number of:
a) Neutrons
b) Protons
c) Electrons
d) Nucleons
Answer: b) Protons
6. Who discovered the electron?
a) J.J. Thomson
b) Ernest Rutherford
c) Niels Bohr
d) Robert Millikan
Answer: a) J.J. Thomson
7. One mole of any substance contains how many particles?
a) 6.022×10226.022 \times 10^{22}6.022×1022
b) 6.022×10236.022 \times 10^{23}6.022×1023
c) 6.022×10246.022 \times 10^{24}6.022×1024
d) 6.022×10256.022 \times 10^{25}6.022×1025
Answer: b) 6.022×10236.022 \times 10^{23}6.022×1023
8. 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
9. The number of moles in 22 g of CO₂ (molar mass = 44 g/mol) is:
a) 0.25
b) 0.5
c) 1
d) 2
Answer: b) 0.5
10. What is the percentage composition of oxygen in H₂O?
a) 11.2%
b) 33.3%
c) 66.7%
d) 88.9%
Answer: d) 88.9%
11. Which of the following is an empirical formula?
a) C₆H₁₂O₆
b) CH₂O
c) C₂H₄O₂
d) C₃H₆O₃
Answer: b) CH₂O
12. Calculate the number of atoms in 2 moles of hydrogen gas (H₂):
a) 1.204×10231.204 \times 10^{23}1.204×1023
b) 2.408×10232.408 \times 10^{23}2.408×1023
c) 1.204×10241.204 \times 10^{24}1.204×1024
d) 2.408×10242.408 \times 10^{24}2.408×1024
Answer: d) 2.408×10242.408 \times 10^{24}2.408×1024
13. The bond formed by sharing a pair of electrons is called:
a) Ionic bond
b) Covalent bond
c) Metallic bond
d) Hydrogen bond
Answer: b) Covalent bond
14. What type of bond is present in NaCl?
a) Covalent
b) Ionic
c) Metallic
d) Hydrogen
Answer: b) Ionic
15. Which of the following molecules is polar?
a) CO₂
b) CH₄
c) H₂O
d) O₂
Answer: c) H₂O
16. The octet rule is not obeyed by:
a) NH₃
b) BF₃
c) H₂O
d) CH₄
Answer: b) BF₃
17. What is the shape of a methane (CH₄) molecule?
a) Linear
b) Tetrahedral
c) Trigonal planar
d) Bent
Answer: b) Tetrahedral
18. Hydrogen bonds are strongest in:
a) NH₃
b) H₂O
c) HF
d) HCl
Answer: c) HF
19. What is the boiling point of water at standard atmospheric pressure?
a) 0°C
b) 50°C
c) 100°C
d) 200°C
Answer: c) 100°C
20. Which gas law relates pressure and volume?
a) Boyle’s Law
b) Charles’ Law
c) Avogadro’s Law
d) Ideal Gas Law
Answer: a) Boyle’s Law
21. The value of R (gas constant) in SI units is:
a) 0.0821 atm L/mol K
b) 8.314 J/mol K
c) 1.987 cal/mol K
d) 62.36 L Torr/mol K
Answer: b) 8.314 J/mol K
22. At constant temperature, the pressure of a gas is inversely proportional to its:
a) Volume
b) Temperature
c) Density
d) Mass
Answer: a) Volume
23. Which state of matter has the highest kinetic energy?
a) Solid
b) Liquid
c) Gas
d) Plasma
Answer: d) Plasma
24. The process of a solid directly converting into gas is called:
a) Condensation
b) Sublimation
c) Evaporation
d) Deposition
Answer: b) Sublimation
25. Who is known as the father of the periodic table?
a) Mendeleev
b) Moseley
c) Dalton
d) Bohr
Answer: a) Mendeleev
26.The element with atomic number 17 is:
a) Fluorine
b) Chlorine
c) Bromine
d) Iodine
Answer: b) Chlorine
27.What is the group number of alkali metals?
a) 1
b) 2
c) 17
d) 18
Answer: a) 1
28.Which of the following is a noble gas?
a) Oxygen
b) Nitrogen
c) Helium
d) Hydrogen
Answer: c) Helium
29.Elements in the same group have:
a) Same atomic number
b) Same valence electrons
c) Same mass number
d) Same density
Answer: b) Same valence electrons
30.The most electronegative element is:
a) Oxygen
b) Chlorine
c) Fluorine
d) Bromine
Answer: c) Fluorine
31. What is the reactant in the reaction: 2H₂ + O₂ → 2H₂O?
a) H₂O
b) H₂
c) O₂
d) Both b and c
Answer: d) Both b and c
32. Balance the equation: C₃H₈ + O₂ → CO₂ + H₂O. The coefficient of O₂ is:
a) 3
b) 4
c) 5
d) 7
Answer: d) 5
33. What is the limiting reagent when 2 moles of H₂ react with 1 mole of O₂?
a) H₂
b) O₂
c) H₂O
d) None
Answer: a) H₂
34. The law of conservation of mass states that:
a) Mass can be created.
b) Mass can be destroyed.
c) Mass cannot be created or destroyed.
d) Mass is variable.
Answer: c) Mass cannot be created or destroyed.
35. In the reaction, Zn + H₂SO₄ → ZnSO₄ + H₂, what is oxidized?
a) H₂SO₄
b) Zn
c) H₂
d) ZnSO₄
Answer: b) Zn
36. Calculate the mass of oxygen required to completely react with 4 g of hydrogen (H₂) to form water (H₂O).
a) 16 g
b) 32 g
c) 8 g
d) 4 g
Answer: b) 32 g
37. Which of the following is a state function?
a) Work
b) Heat
c) Enthalpy
d) Power
Answer: c) Enthalpy
38. The first law of thermodynamics is based on the principle of:
a) Conservation of energy
b) Conservation of mass
c) Conservation of momentum
d) Conservation of temperature
Answer: a) Conservation of energy
39. What is the SI unit of heat energy?
a) Calorie
b) Joule
c) Erg
d) Watt
Answer: b) Joule
40. A process in which no heat is exchanged with the surroundings is called:
a) Isothermal
b) Adiabatic
c) Isochoric
d) Isobaric
Answer: b) Adiabatic
41. If ΔH > 0 for a reaction, the reaction is:
a) Exothermic
b) Endothermic
c) Isothermal
d) Adiabatic
Answer: b) Endothermic
42. Which of the following has the highest entropy?
a) Ice
b) Water
c) Steam
d) Liquid nitrogen
Answer: c) Steam
43. The equilibrium constant KcK_cKc is dimensionless when:
a) Number of moles of reactants = products.
b) Number of moles of reactants > products.
c) Number of moles of reactants < products.
d) None of the above.
Answer: a) Number of moles of reactants = products.
44. The value of KcK_cKc for a reaction depends on:
a) Pressure
b) Temperature
c) Catalyst
d) Concentration
Answer: b) Temperature
45. If Q<KcQ < K_cQ<Kc, the reaction:
a) Is at equilibrium
b) Proceeds forward
c) Proceeds backward
d) Stops
Answer: b) Proceeds forward
46. Which of the following will shift the equilibrium of the reaction N₂ + 3H₂ ↔ 2NH₃ to the right?
a) Increasing pressure
b) Decreasing temperature
c) Removing NH₃
d) All of the above
Answer: d) All of the above
47. Le Chatelier’s principle explains:
a) Reaction kinetics
b) Catalyst action
c) Equilibrium shifts
d) Mole concept
Answer: c) Equilibrium shifts
48. Adding a catalyst to a reaction at equilibrium will:
a) Shift equilibrium to the right
b) Shift equilibrium to the left
c) Speed up both forward and reverse reactions
d) Have no effect on equilibrium position
Answer: c) Speed up both forward and reverse reactions
49. A solution is a:
a) Homogeneous mixture
b) Heterogeneous mixture
c) Compound
d) Suspension
Answer: a) Homogeneous mixture
50. Which of the following is an example of a colloid?
a) Salt water
b) Blood
c) Vinegar
d) Sugar water
Answer: b) Blood
51. The solubility of a gas in water increases with:
a) Increasing temperature
b) Decreasing temperature
c) Decreasing pressure
d) None of the above
Answer: b) Decreasing temperature
52. A solution in which no more solute can dissolve is called:
a) Unsaturated
b) Saturated
c) Supersaturated
d) Dilute
Answer: b) Saturated
53. What is the molality of a solution containing 5 moles of solute in 2 kg of solvent?
a) 2.5 mol/kg
b) 5 mol/kg
c) 10 mol/kg
d) 15 mol/kg
Answer: b) 2.5 mol/kg
54. Raoult’s law applies to:
a) Ideal solutions
b) Colloidal solutions
c) Suspensions
d) Non-ideal solutions
Answer: a) Ideal solutions
55. The SI unit of pressure is:
a) Atmosphere
b) Torr
c) Pascal
d) Bar
Answer: c) Pascal
56. Which acid is present in vinegar?
a) Acetic acid
b) Citric acid
c) Hydrochloric acid
d) Lactic acid
Answer: a) Acetic acid
57. Avogadro’s law states that equal volumes of gases contain:
a) Equal masses
b) Equal pressure
c) Equal molecules
d) Equal densities
Answer: c) Equal molecules
58. Which element is a halogen?
a) Sodium
b) Bromine
c) Calcium
d) Neon
Answer: b) Bromine
59. The substance that increases the rate of a chemical reaction is called:
a) Reactant
b) Product
c) Catalyst
d) Solvent
Answer: c) Catalyst
60. The pH of a neutral solution at 25°C is:
a) 0
b) 7
c) 14
d) 10
Answer: b) 7
Wrapping Up
Understanding some basic concepts of chemistry MCQ is essential for building a strong foundation in the subject. These questions cover key topics like atoms, molecules, chemical reactions, and the periodic table, helping you test and improve your knowledge. By practicing MCQs regularly, you can strengthen your problem-solving skills and identify areas that need more focus. Chemistry becomes easier and more interesting when you approach it step by step. Keep practicing, use reliable resources, and stay curious to learn more. With consistent effort, you can master these basic concepts and excel in your studies or competitive exams. Keep going!
