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. Which of the following represents an element?

The periodic table

A pure substance made up of one type of atom

A compound made up of one type of element

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

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2. Which of the following represents a compound?

Made up of 10 atoms

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

Two words in one word

A pure substance made up of one type of atom

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3. The prefix 10¹⁸ is

Kilo

Exa

Giga

Nano

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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 atoms

Ionic element

Ionic charges

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

6

3

42

21

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

They possess same position in the periodic table

They possess different mass number

They possess same physical properties

They possess same chemical properties

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7. What are the two different types of ions?

Electrons and protons

Polyatomic and multivalent

Polyatomic and compound ions

Negative and positive

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

1.0

1.11

0.90

0.11

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9. 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

One moles of N₂ will produce two moles of NH₃.

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.

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

86% hydrogen and 14% carbon

83% hydrogen and 17% carbon

14% hydrogen and 86% carbon

17% hydrogen and 83% carbon

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

Mg(ClO₄)₂

Al₂O₃

SiO₂

KOH

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12. Percent of calcium in calcium carbonate is

20%

40%

80%

30%

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

M₂C1₂

MC1

MCL₂

MC1₃

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

32.47%

24.51%

66.67%

12.26%

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

44

33

22

11

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

19.97%

50%

20.05%

80.03%

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18. Which of the following is an element?

Gold

Water

Common Salt

Sugar

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

5 moles

5000 mole

10 moles

0.005 mole

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

Protons and neutrons

Electrons and shells

Neutrons and electrons

Protons and electrons

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

Empirical formula x n² = Molecular formula

Empirical formula x √n = Molecular formula

Molecular formula /n = Empirical formula

Empirical formula /n = Molecular formula

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

4 x 6.02 x 10²³

3 x 6.02 x 10²³

6.02 x 10²³ x 2

6.02 x 10²³

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

N₂O₃

N₂O

NO₂

NO

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

Its molecular formula does not exist

Only one molecular formula (CH2) is possible

More than one could be a molecular formula for CH₂

Only one molecular formula (C2H2) is possible

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

112 Cm³

1.12 dm³

2.24 dm³

22.4 dm³

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

Combustion method

All of above

Duma’s method

K. Jeldahl’s method

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

C₃H₆O₃

C₂H₄O₂

CH₂O

C₄H₈O₄

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

H₂O

NaC1

CC1₄

It can be applied to all

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

2 elements and a total of 3 atoms

2 elements and a total of 2 atoms

3 elements and a total of 2 atoms

3 elements and a total of 3 atoms

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

3.01 x 10²²

6.02 x 10²²

3.01 x 10²³

6.02 x 10²³

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

Sublimation

Crystallization

Chromatography

Graham’s Law of diffusion

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32. The percentage of oxygen in NaOH is

40

8

10

60

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

Hund’s rule

Moley’s law

Newton’s law

Dalton’s law

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

79

80

79.5

81

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35. Empirical formula of chloroform is

CHCl₃

CHCl

CH₂C₁₂

CH₃cl

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

6 x 10²²

1.2 x 10²³

12 x 10²³

6 x 10²²

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37. What is a chemical compound?

A mixture of two or more substance

A combination of two or more chemical elements

A subatomic particle

A combination of two protons and two electrons

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38. 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

Nm¯²s¯²

Nil, it is dimensionless constant

Kg m¯¹s¯¹

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

CuO, Cu₂O

CS₂, FeSO₄

NH₃, HC1

H₂S, SO₂

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

To carry out compete combustion

All of these

To reduce the economy of the process

To reduce the time for completion of the reaction

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

Lose electrons

Lose electrons and protons

None of these

Gain electrons and protons

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42. Which one of the following is ambiguous?

A mole of electrons

A mole of hydrogen

A mole of sodium atoms

A mole of potassium ions

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43. The compound having highest percent of oxygen is

C₂H₅OH

CH₃COOH

H₂O

CH₃COCH₃

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44. Difference in density is the basis of

Molecular sieving

Molecular attraction

Gravity separation

Ultrafiltration

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

Water

Vinegar

Oxygen gas

Air

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

SO₂

S₂O₃

SO

SO₃

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47. 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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48. What is the net charge on ferrous ion?

+5

+3

+2

+4

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

Graham’s law of diffusion technique

Fractional distillation technique

Chromatography

Osmosis

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50. 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

Conservation of mass

Constant volume

Multiple proportions

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

Atomic absorption spectrometer

Ultraviolet spectrometer

Mass spectrometer

Infra-red spectrometer

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52. What is a multivalent ion?

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

An ion that can have more than one charge

Some ions can have only one charge

Only negatively charged

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

BaO₂

C₂H₄

C₆H₁₂O₆

H₂O₂

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

0.25

1.00

0.75

0.5

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55. Indicate the incorrect statement form the following

A limiting reactant is used at the end of reaction

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

Stoichiometric calculation can only be done if no side reaction happen

Actual yield is always less than theoretical yield

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

1.99 x 10¯²³

4.65 x 10¯²³

1.37 x 10²²

7.31 x 10¯²³

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

2, 1, 1, 2, 1

1, 1, 2, 2, 1

2, 2, 1, 1, 1

2, 2, 1, 2, 1

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

Gold

Soil

Sodium Chloride

Water

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59. What are the parts of an atom?

Ions, electrons, neutrons, water

Nucleus, element, carbon, space

Protons, neutrons, nucleus, mass

Protons, neutrons, electrons, nucleus

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

Nucleus

Ions

Neutrons

Protons

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61. The modern atomic weight scale is based on

C¹³

C¹²

O¹⁶

H¹

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62. 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 protons

The atomic mass subtracted the number of electrons

The atomic mass plus the number of electrons

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63. 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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64. Isotopes differ in the

Number of neutrons

Number of electrons

Number of atoms

Number of protons

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

Water

Methane

Sugar

Carbon dioxide

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

Mixture

Crystal

Element

Compound

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

1.6 Na

2.4 Na

4.2 Na

3.2 Na

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68. 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?

Cu₂Cl₃

CuCl

CuCl₂

CuCl₃

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

0.0732

0.0704

0.210

0.0233

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70. Diameter of an atom is in the range of

0.2 nm

2 x10¯¹⁰

0.2 m

0.2 Pm

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

2:16:1

2:16:2

1:16:2

1:1:1

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