MDCAT Fundamental Concepts of Chemistry Test Online MCQs

MDCAT Fundamental Concepts of Chemistry Online Test

Prepare for MDCAT Chemistry with this online MCQ test on Fundamental Concepts of Chemistry. This quiz covers key basics such as atomic mass, moles, empirical and molecular formulas, and chemical calculations, aligned with the MDCAT 2025 syllabus to build a strong foundation for the subject.

MDCAT 2025 Basic Concepts Online Test

MDCAT Chemistry Basic Concepts Test Question with Answer

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1. If the empirical formula of compound is CH₂. Which of the following is true about its molecular formula?

Its molecular formula does not exist

More than one could be a molecular formula for CH₂

Only one molecular formula (CH2) is possible

Only one molecular formula (C2H2) is possible

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2. Which of the following statements is FALSE for the chemical equation given below in which nitrogen gas reacts with hydrogen gas to form ammonia gas assuming the reaction goes to completion?
N₂ + 3H₂ → 2NH₃

The reaction of three moles of hydrogen gas will produce 17 g of ammonia

The reaction of one mole of H₂ will produce 2/3 moles of NH₃.

One molecule of nitrogen requires three molecules of hydrogen for complete reaction.

One moles of N₂ will produce two moles of NH₃.

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3. What is the percent water in hydrated calcium chloride (CaC1₂ 2H₂O)?

66.67%

32.47%

24.51%

12.26%

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4. How many moles of KBrO₃ are required to prepare 0.0700 moles of Br₂ according to the reaction: KBrO₃ + 5KBr + 6HNO₃ → 6KNO₃ + 3Br₂ + 3H₂O

0.210

0.0732

0.0233

0.0704

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5. For which of the following terms empirical formula cannot be applied?

It can be applied to all

CC1₄

H₂O

NaC1

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6. Among the following pairs, the one which illustrates the law of multiple proportions is

H₂S, SO₂

NH₃, HC1

CuO, Cu₂O

CS₂, FeSO₄

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7. What are the two different types of ions?

Polyatomic and compound ions

Electrons and protons

Negative and positive

Polyatomic and multivalent

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8. Irrespective of the source, pure sample of water always yields 88.89% mass of oxygen and 11.11% mass of hydrogen. This is explained by the law of

Multiple proportions

Constant volume

Definite proportions

Conservation of mass

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9. The prefix 10¹⁸ is

Giga

Exa

Nano

Kilo

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10. The set of numerical coefficients that balances the chemical equation K₂CrO₄ + CH1 → K₂Cr₂O₇ + KC1 + H₂O

1, 1, 2, 2, 1

2, 2, 1, 1, 1

2, 2, 1, 2, 1

2, 1, 1, 2, 1

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11. An anhydrous salt of copper is found to contain 52.7% chlorine and 47.3% copper by mass. What is the empirical formula for this salt?

CuCl₃

CuCl

Cu₂Cl₃

CuCl₂

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12. What does the atomic number of an atom represent?

Neutrons and electrons

Protons and neutrons

Electrons and shells

Protons and electrons

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13. Which of the following represents an element?

A compound made up of one type of element

A pure substance made up of one type of atom

The periodic table

A pure substance made up of two or more types of atoms

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14. An oxide of nitrogen contain 36.8% nitrogen and 63.2% oxygen by mass. Calculate its empirical formula.

NO₂

NO

N₂O₃

N₂O

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15. Bromine has two isotopes having the relative abundances as ⁷⁵₃₉Br = 50.51% and ⁸¹₃₅Br= 49.49%. The average atomic mass of bromine is

81

80

79.5

79

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16. Empirical formula of chloroform is

CH₂C₁₂

CH₃cl

CHCl₃

CHCl

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17. One of the substances is used to absorb CO₂ gas in combustion analysis. Which is that substance?

SiO₂

Mg(ClO₄)₂

Al₂O₃

KOH

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18. Since atoms are neutral, the number of electrons is equal to the number of:

Protons

Nucleus

Ions

Neutrons

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19. A ring contains 1.2g of diamond. How many number of carbon atoms are in diamond?

6.02 x 10²²

6.02 x 10²³

3.01 x 10²³

3.01 x 10²²

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20. The hydrogen phosphate of certain metal has formula MHPO₄. The formula of metal chloride would be

M₂C1₂

MC1₃

MC1

MCL₂

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21. 1 mole of CH₄ contains

1.81 x 10²³ molecules of CH₄

6.02 x 10²³ atoms of H

3.0 g of carbon

4 g-atom of hydrogen

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22. Ayesha required an aqueous solution of sodium chloride. She made the solution by dissolving salt in:

Oxygen gas

Air

Vinegar

Water

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23. What do you call pure substances that are formed from the attraction between positive ions and negative ions?

Ionic compounds

Ionic charges

Ionic element

Ionic atoms

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24. A compound contains 6.0 g of carbon and 1.0 g of hydrogen. The percent composition of the compound is:

83% hydrogen and 17% carbon

14% hydrogen and 86% carbon

17% hydrogen and 83% carbon

86% hydrogen and 14% carbon

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25. Percent of calcium in calcium carbonate is

40%

80%

30%

20%

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26. Calculate the number of moles of CaCO₃ (Formula weight = 100) in a sample that weighs 25.0 grams.

0.5

0.25

1.00

0.75

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27. How can you separate the mixture of two gases of different atomic masses?

Crystallization

Chromatography

Graham’s Law of diffusion

Sublimation

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28. Which of the following could be an empirical formula?

H₂O₂

BaO₂

C₆H₁₂O₆

C₂H₄

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29. Which of the following is a pure substance made up of two or more types of atoms or elements?

Crystal

Compound

Element

Mixture

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30. The Number of oxygen atoms in 4.4 g of CO2 is approximately

12 x 10²³

6 x 10²²

6 x 10²²

1.2 x 10²³

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31. What are the parts of an atom?

Protons, neutrons, nucleus, mass

Nucleus, element, carbon, space

Protons, neutrons, electrons, nucleus

Ions, electrons, neutrons, water

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32. How will you separate a mixture of two gases?

Chromatography

Osmosis

Graham’s law of diffusion technique

Fractional distillation technique

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33. Which one of the following is ambiguous?

A mole of potassium ions

A mole of sodium atoms

A mole of hydrogen

A mole of electrons

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34. What is correct relationship between empirical and molecular formulas?

Empirical formula /n = Molecular formula

Molecular formula /n = Empirical formula

Empirical formula x √n = Molecular formula

Empirical formula x n² = Molecular formula

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35. How many elements are present in two molecules of aspirin? The formula for aspirin is C₉H₈O₄.

3

42

6

21

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36. The percentage of oxygen in NaOH is

10

60

40

8

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37. Indicate the incorrect statement form the following

Actual yield is always less than theoretical yield

Stoichiometric calculation can only be done if no side reaction happen

A limiting reactant is used at the end of reaction

The empirical and molecular formula of some of the compounds are same

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38. If Na is Avogadro’s number, then number of valence electrons in 4.2 g of nitride ions N³¯ is

3.2 Na

2.4 Na

4.2 Na

1.6 Na

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39. Balance the following equation using minimum integral coefficients: (NH₃ + O₂ → NO₂ + H₂O) Find the stoichiometric coefficient for oxygen gas O₂:

1

7

4

3

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40. Which of the following is NOT true of matter on the Earth?

Matter is always composed of atoms

Matter always consists of molecules

All matter contains chemical elements

All substances are made of matter

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41. Which law directly explains the law of conservation of mass?

Newton’s law

Dalton’s law

Hund’s rule

Moley’s law

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42. The compound having highest percent of oxygen is

CH₃COCH₃

CH₃COOH

H₂O

C₂H₅OH

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43. Water (H₂O) is a common compound made up of:

2 elements and a total of 3 atoms

3 elements and a total of 3 atoms

2 elements and a total of 2 atoms

3 elements and a total of 2 atoms

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44. Copper (II) oxide is mixed with organic compound during combustion. The purpose is

To reduce the time for completion of the reaction

All of these

To carry out compete combustion

To reduce the economy of the process

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45. How many number of ions are there in 98 grams of sulphate ions?

6.02 x 10²³

4 x 6.02 x 10²³

3 x 6.02 x 10²³

6.02 x 10²³ x 2

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46. Which of the following is NOT a pure substance?

Water

Gold

Sodium Chloride

Soil

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47. Which of the following is an element?

Sugar

Water

Gold

Common Salt

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48. The volume occupied by 28 gram of N₂ at STP?

1.12 dm³

22.4 dm³

112 Cm³

2.24 dm³

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49. Which of the following method is used to estimate oxygen in an organic compound?

All of above

Combustion method

Duma’s method

K. Jeldahl’s method

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50. Most atoms are neutral, to become a positive ion the atom must:

Lose electrons and protons

None of these

Lose electrons

Gain electrons and protons

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Page 3 of 3

51. The empirical formula of the compound having 50% sulphur and 50% oxygen by mass is

SO₃

SO

S₂O₃

SO₂

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52. The empirical formula of a compound is CH₂O and its molecular mass is 120. The molecular formula of the compound is

C₂H₄O₂

C₃H₆O₃

C₄H₈O₄

CH₂O

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53. A gaseous mixture contains 50% helium and 50% methane by volume. What is the percent by weight of methane in the mixture?

50%

20.05%

19.97%

80.03%

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54. How many moles of Helium gas occupy 22.4 L at 0°C at 1 atm. Pressure?

1.0

1.11

0.11

0.90

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55. To differentiate between C-12, C-13 and C-14, the instrument that you would use is

Ultraviolet spectrometer

Mass spectrometer

Atomic absorption spectrometer

Infra-red spectrometer

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56. Vapor density of a gas is 22. What is its molecular mass?

11

44

22

33

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57. What are the ratios among the volumes of gases of ³²O₂,²H₂, and ¹⁶CH₄ if equal mass of each gas is taken?

1:16:2

1:1:1

2:16:2

2:16:1

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58. How do you calculate the number of neutrons in an atom?

The atomic mass plus the number of electrons

The atomic mass plus the number of protons

The atomic mass subtracted the number of protons

The atomic mass subtracted the number of electrons

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59. Calculate the weight, in grams, of one molecule of carbon dioxide, CO₂.

1.37 x 10²²

7.31 x 10¯²³

1.99 x 10¯²³

4.65 x 10¯²³

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60. The coefficient of viscosity η of a fluid moving steadily between two surfaces is given by the formula, f = η dV/dx where f is the frictional force on the fluid. A is an area in the fluid and dV/dx is the velocity gradient inside the fluid at that area. The S.I. unit of viscosity coefficient η is given as,

Nil, it is dimensionless constant

Nm¯²s¯²

Kg m¯¹s¯¹

Newton

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61. What is the net charge on ferrous ion?

+3

+4

+2

+5

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62. Which of the following statements is wrong about isotopes?

They possess same chemical properties

They possess different mass number

They possess same physical properties

They possess same position in the periodic table

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63. Difference in density is the basis of

Gravity separation

Molecular attraction

Molecular sieving

Ultrafiltration

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64. The modern atomic weight scale is based on

H¹

C¹³

O¹⁶

C¹²

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65. Diameter of an atom is in the range of

0.2 m

0.2 nm

0.2 Pm

2 x10¯¹⁰

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66. Molecular compounds can be found in all three states of matter at room temperature. Which molecule compound is a liquid at room temperature?

Sugar

Methane

Water

Carbon dioxide

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67. Isotopes differ in the

Number of protons

Number of neutrons

Number of electrons

Number of atoms

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68. Which of the following represents a compound?

Two words in one word

Pure substances made up to of 2 or more types of atoms

A pure substance made up of one type of atom

Made up of 10 atoms

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69. How many moles of CO₂ are present in 220 mg?

10 moles

5 moles

5000 mole

0.005 mole

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70. What is a multivalent ion?

Some ions can have only one charge

An ion that can have more than one charge

Only negatively charged

Ions that are made of more than one type of atom and act as one

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71. What is a chemical compound?

A combination of two protons and two electrons

A mixture of two or more substance

A combination of two or more chemical elements

A subatomic particle

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