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

1.2 x 10²³

6 x 10²²

6 x 10²²

12 x 10²³

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

MC1₃

MC1

MCL₂

M₂C1₂

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

Ionic compounds

Ionic charges

Ionic atoms

Ionic element

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5. Which of the following represents an 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

A compound made up of one type of element

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

H₂O

NaC1

It can be applied to all

CC1₄

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7. Diameter of an atom is in the range of

2 x10¯¹⁰

0.2 m

0.2 nm

0.2 Pm

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

17% hydrogen and 83% carbon

14% hydrogen and 86% carbon

86% hydrogen and 14% carbon

83% hydrogen and 17% carbon

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

NO₂

N₂O₃

N₂O

NO

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10. The prefix 10¹⁸ is

Kilo

Giga

Nano

Exa

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11. The percentage of oxygen in NaOH is

40

60

10

8

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

1.99 x 10¯²³

1.37 x 10²²

7.31 x 10¯²³

4.65 x 10¯²³

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

Al₂O₃

SiO₂

Mg(ClO₄)₂

KOH

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

Oxygen gas

Water

Vinegar

Air

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

6.02 x 10²³

3.01 x 10²²

6.02 x 10²²

3.01 x 10²³

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

Only one molecular formula (CH2) is possible

Only one molecular formula (C2H2) is possible

More than one could be a molecular formula for CH₂

Its molecular formula does not exist

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17. What is a multivalent ion?

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

Some ions can have only one charge

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

S₂O₃

SO₃

SO₂

SO

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19. Percent of calcium in calcium carbonate is

80%

20%

40%

30%

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20. 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,

Newton

Kg m¯¹s¯¹

Nil, it is dimensionless constant

Nm¯²s¯²

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21. Which of the following represents a compound?

Two words in one word

A pure substance made up of one type of atom

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

Made up of 10 atoms

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

42

21

6

3

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24. Empirical formula of chloroform is

CHCl

CHCl₃

CH₃cl

CH₂C₁₂

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25. 1 mole of CH₄ contains

4 g-atom of hydrogen

1.81 x 10²³ molecules of CH₄

3.0 g of carbon

6.02 x 10²³ atoms of H

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

79.5

80

79

81

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

Mass spectrometer

Ultraviolet spectrometer

Atomic absorption spectrometer

Infra-red spectrometer

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

1.00

0.25

0.5

0.75

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29. 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

1.6 Na

4.2 Na

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30. What is the net charge on ferrous ion?

+2

+5

+3

+4

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31. 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

Definite proportions

Multiple proportions

Conservation of mass

Constant volume

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

3 elements and a total of 2 atoms

2 elements and a total of 3 atoms

2 elements and a total of 2 atoms

3 elements and a total of 3 atoms

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

Chromatography

Osmosis

Graham’s law of diffusion technique

Fractional distillation technique

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

5000 mole

10 moles

0.005 mole

5 moles

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35. What is a chemical compound?

A combination of two or more chemical elements

A mixture of two or more substance

A combination of two protons and two electrons

A subatomic particle

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36. What are the two different types of ions?

Polyatomic and compound ions

Negative and positive

Polyatomic and multivalent

Electrons and protons

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

Protons and neutrons

Neutrons and electrons

Protons and electrons

Electrons and shells

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38. Isotopes differ in the

Number of protons

Number of neutrons

Number of atoms

Number of electrons

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

2.24 dm³

1.12 dm³

112 Cm³

22.4 dm³

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40. Which one of the following is ambiguous?

A mole of electrons

A mole of potassium ions

A mole of hydrogen

A mole of sodium atoms

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41. The modern atomic weight scale is based on

O¹⁶

C¹³

C¹²

H¹

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

C₂H₄O₂

C₄H₈O₄

CH₂O

C₃H₆O₃

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43. 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

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

One moles of N₂ will produce two moles of NH₃.

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.

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

C₂H₄

C₆H₁₂O₆

H₂O₂

BaO₂

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45. 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

2:16:1

2:16:2

1:1:1

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

6.02 x 10²³

6.02 x 10²³ x 2

3 x 6.02 x 10²³

4 x 6.02 x 10²³

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

0.0233

0.0732

0.210

0.0704

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48. The compound having highest percent of oxygen is

H₂O

CH₃COCH₃

C₂H₅OH

CH₃COOH

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

66.67%

12.26%

24.51%

32.47%

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

Empirical formula x √n = Molecular formula

Empirical formula x n² = Molecular formula

Empirical formula /n = Molecular formula

Molecular formula /n = Empirical formula

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

To reduce the economy of the process

All of these

To reduce the time for completion of the reaction

To carry out compete combustion

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

Nucleus

Protons

Ions

Neutrons

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

K. Jeldahl’s method

All of above

Duma’s method

Combustion method

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

4

3

7

1

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

The atomic mass subtracted the number of protons

The atomic mass plus the number of electrons

The atomic mass subtracted the number of electrons

The atomic mass plus the number of protons

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57. Indicate the incorrect statement form the following

Actual yield is always less than theoretical yield

A limiting reactant is used at the end of reaction

Stoichiometric calculation can only be done if no side reaction happen

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

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

Sodium Chloride

Soil

Gold

Water

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

11

33

44

22

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

0.90

1.11

1.0

0.11

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

Newton’s law

Dalton’s law

Moley’s law

Hund’s rule

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

All substances are made of matter

Matter is always composed of atoms

All matter contains chemical elements

Matter always consists of molecules

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63. 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?

CuCl

CuCl₂

CuCl₃

Cu₂Cl₃

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

They possess same chemical properties

They possess same position in the periodic table

They possess different mass number

They possess same physical properties

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65. What are the parts of an atom?

Protons, neutrons, electrons, nucleus

Ions, electrons, neutrons, water

Protons, neutrons, nucleus, mass

Nucleus, element, carbon, space

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66. Which of the following is an element?

Common Salt

Sugar

Water

Gold

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

Chromatography

Graham’s Law of diffusion

Sublimation

Crystallization

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68. Difference in density is the basis of

Ultrafiltration

Molecular sieving

Gravity separation

Molecular attraction

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

2, 2, 1, 1, 1

1, 1, 2, 2, 1

2, 1, 1, 2, 1

2, 2, 1, 2, 1

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

Methane

Sugar

Carbon dioxide

Water

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

Compound

Element

Mixture

Crystal

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