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 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 moles of N₂ will produce two moles of NH₃.

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

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

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

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

22.4 dm³

1.12 dm³

2.24 dm³

112 Cm³

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3. The prefix 10¹⁸ is

Nano

Exa

Kilo

Giga

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

Ions

Neutrons

Protons

Nucleus

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5. What is a multivalent ion?

An ion that can have more than one charge

Some ions can have only one charge

Only negatively charged

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

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6. What are the two different types of ions?

Polyatomic and compound ions

Polyatomic and multivalent

Negative and positive

Electrons and protons

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

Newton’s law

Hund’s rule

Dalton’s law

Moley’s law

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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

Conservation of mass

Multiple proportions

Constant volume

Definite proportions

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9. 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

17% hydrogen and 83% carbon

14% hydrogen and 86% carbon

83% hydrogen and 17% carbon

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10. 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?

CuCl₂

Cu₂Cl₃

CuCl

CuCl₃

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

42

21

3

6

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

22

33

44

11

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13. What are the parts of an atom?

Protons, neutrons, electrons, nucleus

Nucleus, element, carbon, space

Protons, neutrons, nucleus, mass

Ions, electrons, neutrons, water

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

Air

Water

Vinegar

Oxygen gas

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

1.6 Na

4.2 Na

2.4 Na

3.2 Na

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16. Difference in density is the basis of

Molecular attraction

Gravity separation

Ultrafiltration

Molecular sieving

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

Gold

Soil

Water

Sodium Chloride

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18. Which of the following is an element?

Common Salt

Water

Sugar

Gold

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

NO

N₂O₃

NO₂

N₂O

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

They possess same physical properties

They possess same chemical properties

They possess same position in the periodic table

They possess different mass number

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

K. Jeldahl’s method

Duma’s method

All of above

Combustion method

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

Osmosis

Chromatography

Graham’s law of diffusion technique

Fractional distillation technique

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

3.01 x 10²³

3.01 x 10²²

6.02 x 10²³

6.02 x 10²²

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24. 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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25. Percent of calcium in calcium carbonate is

30%

40%

80%

20%

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

Empirical formula /n = Molecular formula

Empirical formula x √n = Molecular formula

Molecular formula /n = Empirical formula

Empirical formula x n² = Molecular formula

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27. 1 mole of CH₄ contains

6.02 x 10²³ atoms of H

1.81 x 10²³ molecules of CH₄

3.0 g of carbon

4 g-atom of hydrogen

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

0.11

1.0

1.11

0.90

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

Ionic atoms

Ionic element

Ionic compounds

Ionic charges

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

1

7

3

4

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

5000 mole

10 moles

0.005 mole

5 moles

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

Crystallization

Chromatography

Sublimation

Graham’s Law of diffusion

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34. 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

0.0704

0.0732

0.210

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35. What is the net charge on ferrous ion?

+5

+2

+3

+4

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

BaO₂

C₂H₄

C₆H₁₂O₆

H₂O₂

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

3 elements and a total of 3 atoms

3 elements and a total of 2 atoms

2 elements and a total of 3 atoms

2 elements and a total of 2 atoms

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38. What is a chemical compound?

A combination of two protons and two electrons

A combination of two or more chemical elements

A subatomic particle

A mixture of two or more substance

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

1:1:1

2:16:1

2:16:2

1:16:2

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40. 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 (C2H2) is possible

Only one molecular formula (CH2) is possible

More than one could be a molecular formula for CH₂

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

NaC1

It can be applied to all

CC1₄

H₂O

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42. Indicate the incorrect statement form the following

Actual yield is always less than theoretical yield

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

A limiting reactant is used at the end of reaction

Stoichiometric calculation can only be done if no side reaction happen

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43. Which one of the following is ambiguous?

A mole of electrons

A mole of hydrogen

A mole of potassium ions

A mole of sodium atoms

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

3 x 6.02 x 10²³

4 x 6.02 x 10²³

6.02 x 10²³ x 2

6.02 x 10²³

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

None of these

Lose electrons

Gain electrons and protons

Lose electrons and protons

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46. The modern atomic weight scale is based on

C¹³

C¹²

O¹⁶

H¹

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47. Empirical formula of chloroform is

CHCl

CHCl₃

CH₂C₁₂

CH₃cl

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

12.26%

24.51%

66.67%

32.47%

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

6 x 10²²

6 x 10²²

12 x 10²³

1.2 x 10²³

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

Matter always consists of molecules

All substances are made of matter

All matter contains chemical elements

Matter is always composed of atoms

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

79

81

79.5

80

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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

CH₂O

C₃H₆O₃

C₂H₄O₂

C₄H₈O₄

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

SiO₂

KOH

Al₂O₃

Mg(ClO₄)₂

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

19.97%

80.03%

20.05%

50%

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55. Isotopes differ in the

Number of electrons

Number of atoms

Number of neutrons

Number of protons

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

0.75

1.00

0.25

0.5

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

SO

S₂O₃

SO₂

SO₃

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58. 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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59. 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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60. To differentiate between C-12, C-13 and C-14, the instrument that you would use is

Infra-red spectrometer

Ultraviolet spectrometer

Mass spectrometer

Atomic absorption spectrometer

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61. The percentage of oxygen in NaOH is

8

40

10

60

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62. Diameter of an atom is in the range of

0.2 m

0.2 nm

2 x10¯¹⁰

0.2 Pm

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

The atomic mass subtracted the number of electrons

The atomic mass plus the number of protons

The atomic mass subtracted the number of protons

The atomic mass plus the number of electrons

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

Electrons and shells

Neutrons and electrons

Protons and neutrons

Protons and electrons

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

CuO, Cu₂O

H₂S, SO₂

CS₂, FeSO₄

NH₃, HC1

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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?

Methane

Sugar

Water

Carbon dioxide

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

All of these

To reduce the time for completion of the reaction

To carry out compete combustion

To reduce the economy of the process

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68. Which of the following represents an element?

The periodic table

A compound made up of one type of element

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

A pure substance made up of one type of atom

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69. The compound having highest percent of oxygen is

C₂H₅OH

CH₃COCH₃

H₂O

CH₃COOH

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

MC1

M₂C1₂

MCL₂

MC1₃

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