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

22

33

44

11

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2. Difference in density is the basis of

Molecular attraction

Molecular sieving

Ultrafiltration

Gravity separation

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

Moley’s law

Hund’s rule

Dalton’s law

Newton’s law

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

Mixture

Element

Crystal

Compound

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5. What is a chemical compound?

A subatomic particle

A mixture of two or more substance

A combination of two protons and two electrons

A combination of two or more chemical elements

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

Soil

Sodium Chloride

Water

Gold

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7. Which of the following is an element?

Common Salt

Sugar

Gold

Water

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8. Indicate the incorrect statement form the following

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

Stoichiometric calculation can only be done if no side reaction happen

A limiting reactant is used at the end of reaction

Actual yield is always less than theoretical yield

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9. 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

More than one could be a molecular formula for CH₂

Its molecular formula does not exist

Only one molecular formula (C2H2) is possible

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

MC1₃

MC1

MCL₂

M₂C1₂

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

Matter always consists of molecules

All matter contains chemical elements

Matter is always composed of atoms

All substances are made of matter

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12. The compound having highest percent of oxygen is

H₂O

C₂H₅OH

CH₃COOH

CH₃COCH₃

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

3

7

4

1

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

Methane

Water

Carbon dioxide

Sugar

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

Sublimation

Graham’s Law of diffusion

Crystallization

Chromatography

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

80

79

81

79.5

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17. What are the parts of an atom?

Ions, electrons, neutrons, water

Protons, neutrons, electrons, nucleus

Protons, neutrons, nucleus, mass

Nucleus, element, carbon, space

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18. 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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19. How will you separate a mixture of two gases?

Fractional distillation technique

Graham’s law of diffusion technique

Chromatography

Osmosis

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

It can be applied to all

CC1₄

NaC1

H₂O

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21. Which of the following represents an element?

A pure substance made up of one type of atom

The periodic table

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

12.26%

24.51%

66.67%

32.47%

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

Lose electrons and protons

None of these

Gain electrons and protons

Lose electrons

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24. 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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25. What is the net charge on ferrous ion?

+4

+2

+5

+3

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26. Isotopes differ in the

Number of neutrons

Number of electrons

Number of protons

Number of atoms

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

80.03%

50%

19.97%

20.05%

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

3 x 6.02 x 10²³

6.02 x 10²³ x 2

6.02 x 10²³

4 x 6.02 x 10²³

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29. 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

17% hydrogen and 83% carbon

86% hydrogen and 14% carbon

14% hydrogen and 86% carbon

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

2:16:2

2:16:1

1:16:2

1:1:1

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

0.5

0.75

1.00

0.25

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

3 elements and a total of 2 atoms

3 elements and a total of 3 atoms

2 elements and a total of 2 atoms

2 elements and a total of 3 atoms

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33. 1 mole of CH₄ contains

4 g-atom of hydrogen

6.02 x 10²³ atoms of H

1.81 x 10²³ molecules of CH₄

3.0 g of carbon

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34. 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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35. 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 one mole of H₂ will produce 2/3 moles of NH₃.

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

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36. The prefix 10¹⁸ is

Kilo

Nano

Giga

Exa

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37. The modern atomic weight scale is based on

C¹²

O¹⁶

H¹

C¹³

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

1.11

0.90

0.11

1.0

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

NO

N₂O

N₂O₃

NO₂

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

6.02 x 10²³

3.01 x 10²²

3.01 x 10²³

6.02 x 10²²

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41. Empirical formula of chloroform is

CH₂C₁₂

CHCl₃

CH₃cl

CHCl

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42. 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

Kg m¯¹s¯¹

Nil, it is dimensionless constant

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43. 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

Constant volume

Conservation of mass

Definite proportions

Multiple proportions

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44. 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

0.0704

0.0233

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45. Which one of the following is ambiguous?

A mole of potassium ions

A mole of hydrogen

A mole of sodium atoms

A mole of electrons

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

They possess same physical properties

They possess different mass number

They possess same chemical properties

They possess same position in the periodic table

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

Vinegar

Water

Air

Oxygen gas

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48. Diameter of an atom is in the range of

0.2 Pm

0.2 nm

0.2 m

2 x10¯¹⁰

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

Neutrons

Protons

Nucleus

Ions

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

1.2 x 10²³

6 x 10²²

12 x 10²³

6 x 10²²

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51. What are the two different types of ions?

Polyatomic and multivalent

Negative and positive

Electrons and protons

Polyatomic and compound ions

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52. 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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53. 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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54. Which of the following method is used to estimate oxygen in an organic compound?

Combustion method

Duma’s method

All of above

K. Jeldahl’s method

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55. Percent of calcium in calcium carbonate is

40%

20%

80%

30%

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

Protons and electrons

Protons and neutrons

Electrons and shells

Neutrons and electrons

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

H₂S, SO₂

NH₃, HC1

CS₂, FeSO₄

CuO, Cu₂O

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

5 moles

0.005 mole

10 moles

5000 mole

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

To reduce the economy of the process

All of these

To carry out compete combustion

To reduce the time for completion of the reaction

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

1.6 Na

3.2 Na

4.2 Na

2.4 Na

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61. 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

CuCl₂

Cu₂Cl₃

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

42

6

21

3

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

4.65 x 10¯²³

1.37 x 10²²

1.99 x 10¯²³

7.31 x 10¯²³

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

The atomic mass subtracted the number of electrons

The atomic mass subtracted the number of protons

The atomic mass plus the number of protons

The atomic mass plus the number of electrons

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

BaO₂

H₂O₂

C₂H₄

C₆H₁₂O₆

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

SO₃

SO

S₂O₃

SO₂

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

2, 2, 1, 2, 1

2, 1, 1, 2, 1

2, 2, 1, 1, 1

1, 1, 2, 2, 1

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

1.12 dm³

22.4 dm³

2.24 dm³

112 Cm³

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

Molecular formula /n = Empirical formula

Empirical formula /n = Molecular formula

Empirical formula x √n = Molecular formula

Empirical formula x n² = Molecular formula

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71. The percentage of oxygen in NaOH is

40

10

60

8

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