MDCAT Fundamentals of Chemistry MCQs

This comprehensive set of MCQs on the Fundamentals of Chemistry is designed to cover all essential topics required for success in the Medical and Dental College Admission Test (MDCAT). Focused on key subjects such as atomic structure, chemical bonding, periodic table trends, and basic chemical reactions, these MCQs are crafted to help aspiring medical and dental students build a solid foundation in chemistry and its application in health sciences.

Who should practice Fundamentals of Chemistry MCQs?

Students preparing for the MDCAT who wish to deepen their understanding of core chemistry principles and their relevance to medical studies.
Individuals seeking to enhance their knowledge of topics like chemical equilibrium, thermodynamics, and stoichiometry, which are critical for various medical and dental disciplines.
University students targeting high-yield topics like molecular interactions, acid-base chemistry, and organic compounds.
Anyone aiming to strengthen their foundational understanding of chemical reactions and processes that underpin human physiology and biochemistry.
Candidates focused on developing critical thinking and problem-solving skills in chemistry, a key subject for success in the MDCAT.
Suitable for all students preparing for the MDCAT, including those looking to improve their analytical abilities and gain confidence in tackling chemistry questions.

1. What is the unit used to express atomic mass?

A) Kilograms
B) Grams
C) Atomic Mass Unit
D) Milligrams

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2. The empirical formula of a compound shows the:

A) Actual number of atoms
B) Simplest whole-number ratio of atoms
C) Exact mass of each atom
D) Molecular structure

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3. Which of the following represents a molecular formula?

A) H₂O
B) H
C) HO
D) O₂

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4. The concept of mole relates to:

A) The number of protons in an atom
B) The number of atoms in one mole
C) The volume of a gas at STP
D) The energy levels of an atom

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5. Avogadro’s number is defined as:

A) 6.022 × 10²²
B) 6.022 × 10²³
C) 1.602 × 10⁻¹⁹
D) 9.109 × 10⁻³¹

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6. In stoichiometry, mole ratios are derived from:

A) Empirical formulas
B) The coefficients in a balanced chemical equation
C) Atomic numbers
D) Reaction rates

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7. Which of the following is the limiting reactant?

A) The substance that is left over after the reaction
B) The reactant that determines the amount of product
C) The substance that is consumed first
D) The catalyst of the reaction

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8. The percentage yield is calculated using the formula:

A) (Actual yield / Theoretical yield) × 100
B) (Theoretical yield / Actual yield) × 100
C) (Limiting reactant / Excess reactant) × 100
D) (Empirical formula mass / Molecular formula mass) × 100

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9. Which quantum number represents the shape of an orbital?

A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (mₛ)

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10. The s-orbital is spherical in shape. What is the shape of the p-orbital?

A) Spherical
B) Dumbbell
C) Circular
D) Complex

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11. What is the molecular formula of water?

A) H₂O₂
B) HO
C) H₂O
D) OH

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12. The molar mass of a substance is the mass of:

A) One mole of its molecules
B) One atom of the substance
C) One molecule of the substance
D) 6.022 × 10²³ atoms of the substance

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13. What is Avogadro’s number used to calculate?

A) Atomic mass
B) Molecular mass
C) The number of particles in a mole
D) The volume of gases

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14. Which statement is an assumption in stoichiometric calculations?

A) All reactants are in excess
B) Reactions are incomplete
C) Reactions occur with 100% yield
D) Reactions are reversible

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15. What is the maximum number of electrons in an s-orbital?

A) 1
B) 2
C) 6
D) 10

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16. The proton was discovered by:

A) J.J. Thomson
B) Ernest Rutherford
C) James Chadwick
D) Niels Bohr

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17. In stoichiometry, the limiting reactant determines:

A) The amount of excess reactant
B) The maximum amount of product that can be formed
C) The energy of the reaction
D) The rate of reaction

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18. Which of the following best describes empirical formula?

A) Exact formula of a compound
B) Simplest whole-number ratio of atoms
C) Ratio of mass to volume
D) Theoretical yield formula

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19. Quantum numbers define the:

A) Position of an electron
B) Shape and energy of an orbital
C) Number of protons
D) Type of chemical bond

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20. The principal quantum number (n) describes:

A) Shape of the orbital
B) Orientation of the orbital
C) Size and energy level of the orbital
D) Spin of the electron

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21. The limiting reactant in a chemical reaction:

A) Can be reused in the next reaction
B) Limits the amount of product
C) Is always in excess
D) Never reacts

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22. Which of the following is an assumption of stoichiometry?

A) All reactants are consumed
B) All products are gaseous
C) No energy is lost in the reaction
D) All reactions are spontaneous

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23. The electronic configuration of carbon is:

A) 1s² 2s² 2p²
B) 1s² 2s² 2p⁶
C) 1s² 2s² 2p⁴
D) 1s² 2s² 2p³

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24. What is the symbol for the principal quantum number?

A) l
B) n
C) mₗ
D) mₛ

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25. The molecular formula gives:

A) The simplest ratio of atoms
B) The actual number of each type of atom
C) The percentage composition of atoms
D) The charge on each atom

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26. The angular momentum quantum number (l) determines:

A) The size of the orbital
B) The shape of the orbital
C) The orientation of the orbital
D) The spin of the electron

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27. Which of the following is used to calculate percentage yield?

A) Theoretical yield and actual yield
B) Limiting reactant and excess reactant
C) Molecular formula and empirical formula
D) Atomic mass and molar mass

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28. What is the shape of the d-orbital?

A) Spherical
B) Dumbbell
C) Cloverleaf
D) Linear

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29. The quantum number that specifies the orientation of an orbital is:

A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (mₛ)

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30. Which of the following represents Avogadro’s number?

A) 6.022 × 10²³
B) 1.602 × 10⁻¹⁹
C) 9.109 × 10⁻³¹
D) 6.022 × 10²²

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31. The number of protons in an atom is also known as its:

A) Mass number
B) Atomic number
C) Neutron number
D) Quantum number

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32. What is the molecular formula of glucose?

A) CH₂O
B) C₆H₁₂O₆
C) C₆H₆
D) CH₄

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33. The mole is a measure of:

A) Volume
B) Temperature
C) Amount of substance
D) Pressure

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34. Stoichiometry is primarily concerned with:

A) The study of molecular interactions
B) The quantitative relationships in chemical reactions
C) The study of reaction kinetics
D) The shapes of molecules

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35. The maximum number of electrons that can be accommodated in a p-orbital is:

A) 2
B) 4
C) 6
D) 10

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36. The limiting reactant is the one that:

A) Remains after the reaction is complete
B) Is used up first in the reaction
C) Reacts the slowest
D) Speeds up the reaction

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37. What is the empirical formula of a compound that has the molecular formula C₆H₁₂O₆?

A) C₁H₂O₁
B) CHO
C) C₂H₄O₂
D) CH₂O

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38. The shape of an s-orbital is:

A) Spherical
B) Dumbbell
C) Cloverleaf
D) Planar

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39. What does the magnetic quantum number (mₗ) specify?

A) The size of the orbital
B) The energy level of the electron
C) The orientation of the orbital in space
D) The spin direction of the electron

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40. The molar mass of NaCl is approximately:

A) 58.44 g/mol
B) 35.45 g/mol
C) 22.99 g/mol
D) 98.08 g/mol

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41. How many moles of hydrogen are there in 2 moles of H₂O?

A) 1 mole
B) 2 moles
C) 4 moles
D) 6 moles

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42. In stoichiometric calculations, what is typically used as a conversion factor?

A) Mole ratios from the balanced equation
B) Empirical formulas
C) Atomic masses
D) Ionic charges

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43. Which quantum number is associated with the spin of an electron?

A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (mₛ)

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44. A balanced chemical equation is required for:

A) Determining reaction rate
B) Performing stoichiometric calculations
C) Measuring temperature changes
D) Identifying products

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45. What is the molecular formula of methane?

A) CH₄
B) C₃H₈
C) C₂H₆
D) C₄H₁₀

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46. What is the approximate atomic mass of carbon?

A) 1 amu
B) 12 amu
C) 14 amu
D) 16 amu

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47. Which statement is correct about Avogadro’s number?

A) It represents the number of electrons in one atom
B) It is used to calculate atomic mass
C) It is the number of particles in one mole
D) It represents the number of protons in one nucleus

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48. The stoichiometric coefficient in a chemical equation is used to calculate:

A) The mass of products formed
B) The energy released in a reaction
C) The number of moles of reactants and products
D) The speed of the reaction

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49. How many p-orbitals are there in a p-subshell?

A) 1
B) 2
C) 3
D) 5

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50. The quantum number that defines the energy level of an electron is:

A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (mₛ)

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51. What is the empirical formula of C₂H₆O₂?

A) CHO
B) C₂H₄O₂
C) CH₃O
D) CH₂O

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52. Which of the following is a postulate of stoichiometry?

A) Reactions occur in a fixed proportion by mass
B) The limiting reactant is not used up
C) Reactants are always in excess
D) Yield is always 100%

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53. Which of the following represents the number of atoms in one mole?

A) 1.602 × 10⁻¹⁹
B) 6.022 × 10²³
C) 9.109 × 10⁻³¹
D) 1.67 × 10⁻²⁷

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54. In a chemical reaction, if the actual yield is less than the theoretical yield, the percentage yield will be:

A) Greater than 100%
B) Equal to 100%
C) Less than 100%
D) Negative

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55. The discovery of the proton is credited to:

A) J.J. Thomson
B) Ernest Rutherford
C) James Chadwick
D) Robert Millikan

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56. How many electrons can be accommodated in the n=2 energy level?

A) 2
B) 8
C) 10
D) 18

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57. The shape of the p-orbital is:

A) Spherical
B) Dumbbell-shaped
C) Cloverleaf
D) Planar

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58. Which of the following quantum numbers represents the spin of an electron?

A) n
B) l
C) mₗ
D) mₛ

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59. What is the relationship between empirical and molecular formula?

A) Empirical formula is the simplest ratio of atoms, and molecular formula is the actual number of atoms
B) Molecular formula is the ratio of masses, and empirical formula is the molecular mass
C) Both are always the same
D) Empirical formula is always more complex than the molecular formula

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60. The limiting reactant controls the:

A) Amount of reactants left over
B) Rate of reaction
C) Amount of product formed
D) Amount of energy released

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61. How many atoms are there in one mole of oxygen gas (O₂)?

A) 6.022 × 10²²
B) 6.022 × 10²³
C) 1.204 × 10²⁴
D) 3.011 × 10²³

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62. In which subshell do the d-orbitals exist?

A) s
B) p
C) d
D) f

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63. The empirical formula of benzene (C₆H₆) is:

A) C₆H₆
B) CH
C) C₂H₆
D) CH₂

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64. What is the shape of a d-orbital?

A) Spherical
B) Dumbbell
C) Cloverleaf
D) Planar

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65. Which of the following represents the concept of mole ratio in stoichiometry?

A) It shows the ratio of masses of reactants
B) It relates the number of moles of reactants to products
C) It measures reaction rates
D) It describes the reaction mechanism

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66. Avogadro’s number is used to determine:

A) The molar mass of a substance
B) The number of particles in one mole
C) The atomic number of an element
D) The volume of a gas

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67. Which statement about limiting reactants is correct?

A) The limiting reactant is always the one with the lowest mass
B) The limiting reactant controls the amount of products formed
C) The limiting reactant speeds up the reaction
D) The limiting reactant is never consumed

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68. The principal quantum number (n) is related to:

A) The spin of an electron
B) The size and energy of the orbital
C) The shape of the orbital
D) The orientation of the orbital

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69. What is the electronic configuration of oxygen (atomic number 8)?

A) 1s² 2s² 2p⁴
B) 1s² 2s² 2p²
C) 1s² 2s² 2p⁶
D) 1s² 2s¹

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70. The theoretical yield in a chemical reaction refers to:

A) The maximum amount of product that can be formed
B) The amount of reactant consumed
C) The actual yield obtained
D) The amount of energy released

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71. The quantum number that describes the shape of an orbital is:

A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (mₛ)

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72. What is the molecular formula of ethane?

A) CH₄
B) C₂H₆
C) C₃H₈
D) C₂H₄

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73. In a chemical reaction, if 10 grams of reactant produces 7 grams of product, what is the percentage yield?

A) 70%
B) 30%
C) 100%
D) 50%

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74. Which orbital can hold a maximum of 10 electrons?

A) s
B) p
C) d
D) f

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75. The actual yield in a chemical reaction is:

A) Always equal to the theoretical yield
B) Always greater than the theoretical yield
C) The amount of product actually obtained from the reaction
D) The mass of the limiting reactant

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76. The magnetic quantum number (mₗ) determines:

A) The spin of the electron
B) The orientation of the orbital in space
C) The energy level of the orbital
D) The size of the atom

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77. What is the molecular formula of hydrogen peroxide?

A) H₂O
B) H₂O₂
C) HO
D) H₂O₄

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78. Which of the following represents a d-orbital?

A) n = 1
B) l = 2
C) mₗ = -1
D) mₛ = +1/2

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79. What is the shape of an f-orbital?

A) Spherical
B) Dumbbell
C) Complex and multi-lobed
D) Cloverleaf

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80. In stoichiometric calculations, the mole ratio is derived from:

A) The coefficients of a balanced equation
B) The molecular formula of reactants
C) The atomic masses of elements
D) The empirical formula

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81. The molar mass of a substance is the mass of:

A) One atom of the substance
B) One mole of its molecules
C) One molecule of the substance
D) 6.022 × 10²² atoms of the substance

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82. In the electron configuration 1s² 2s² 2p⁶, what does the “2p⁶” represent?

A) 6 protons in the nucleus
B) 6 electrons in the p orbital of the second energy level
C) The number of neutrons
D) 2 electrons in the p orbital of the first energy level

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83. Limiting reactant is also called:

A) Excess reactant
B) Theoretical reactant
C) Reagent in excess
D) Reagent in deficit

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84. The molar mass of H₂SO₄ is approximately:

A) 49 g/mol
B) 98 g/mol
C) 64 g/mol
D) 180 g/mol

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85. Which of the following represents the correct molecular formula of propane?

A) CH₄
B) C₄H₁₀
C) C₃H₈
D) C₂H₄

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86. The first electron shell can hold a maximum of how many electrons?

A) 2
B) 4
C) 6
D) 8

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87. Which quantum number distinguishes the different orbitals within a given energy level?

A) Principal quantum number (n)
B) Angular momentum quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (mₛ)

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88. In a reaction, if 5 grams of product is obtained but the theoretical yield is 10 grams, the percentage yield is:

A) 50%
B) 100%
C) 200%
D) 150%

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89. The concept of limiting reactant applies when:

A) There is an excess of all reactants
B) Reactants are present in the exact required ratio
C) One reactant is in limited supply
D) All products are formed in excess

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90. What is the empirical formula of C₄H₁₀?

A) C₂H₅
B) CH₄
C) CH₃
D) C₂H₂

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91. The molecular formula of a compound represents:

A) The exact number of each type of atom in one molecule
B) The simplest whole-number ratio of atoms in the compound
C) The structure of the molecule
D) The number of bonds between atoms

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92. In quantum mechanics, the spin quantum number (mₛ) refers to:

A) The direction of an electron’s spin
B) The shape of the orbital
C) The energy level of an electron
D) The orientation of the orbital

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93. The limiting reactant is the reactant that:

A) Determines the amount of product formed
B) Is present in excess
C) Reacts the fastest
D) Does not participate in the reaction

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94. The molecular formula of a compound can be identical to its:

A) Atomic mass
B) Empirical formula
C) Percentage composition
D) Quantum number

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95. The empirical formula of C₂H₄ is:

A) CH₂
B) C₂H₆
C) C₂H₂
D) CH₄

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96. How many grams are there in one mole of water (H₂O)?

A) 18 g
B) 20 g
C) 22 g
D) 24 g

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97. The angular momentum quantum number (l) indicates:

A) The shape of the orbital
B) The energy of the orbital
C) The size of the atom
D) The number of neutrons

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98. A p-orbital can hold a maximum of how many electrons?

A) 2
B) 4
C) 6
D) 10

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99. How is the empirical formula related to the molecular formula?

A) Empirical formula is always larger
B) Molecular formula is a multiple of the empirical formula
C) Both are identical
D) Molecular formula is always smaller

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100. The principal quantum number (n) is responsible for:

A) The size and energy of the orbital
B) The shape of the orbital
C) The spin of the electron
D) The orientation of the orbital

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