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ECAT Chemistry Basic Concepts Test Online

Maan AliLast Updated: April 19, 2025

Chemistry Basic Concepts MCQS Online Test

ECAT Chemistry Basic Concepts Chapter Online Test

Total Questions:	71
Time Allowed:	30 Minutes
Total Marks:	71
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	ECAT Entry Test Chemistry Online Test Interview Questions about Chemisttry All Universities Entrance Test Recruitments Tests

ECAT Chemistry Basic Concepts Test

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Page 1 of 3

1. Indicate the incorrect statement form the following

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

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

2. 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 plus the number of electrons

The atomic mass subtracted the number of protons

3. 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

1:16:2

2:16:1

2:16:2

4. 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

Multiple proportions

Constant volume

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

K. Jeldahl’s method

All of above

Combustion method

Duma’s method

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

C₂H₄

H₂O₂

BaO₂

C₆H₁₂O₆

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

Crystal

Compound

Element

Mixture

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

0.25

0.75

1.00

0.5

9. 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 (C2H2) is possible

Only one molecular formula (CH2) is possible

10. Percent of calcium in calcium carbonate is

30%

20%

80%

40%

11. Which of the following is an element?

Sugar

Water

Common Salt

Gold

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

Chromatography

Sublimation

Graham’s Law of diffusion

Crystallization

13. 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

14. 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.

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

One moles of N₂ will produce two moles of NH₃.

15. 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

Cu₂Cl₃

CuCl₂

CuCl

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

3 elements and a total of 3 atoms

2 elements and a total of 2 atoms

3 elements and a total of 2 atoms

2 elements and a total of 3 atoms

17. Empirical formula of chloroform is

CH₃cl

CHCl₃

CHCl

CH₂C₁₂

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

All substances are made of matter

Matter always consists of molecules

All matter contains chemical elements

Matter is always composed of atoms

19. The percentage of oxygen in NaOH is

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

20.05%

19.97%

80.03%

50%

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

0.90

1.0

0.11

1.11

22. What are the two different types of ions?

Polyatomic and compound ions

Electrons and protons

Negative and positive

Polyatomic and multivalent

23. The compound having highest percent of oxygen is

CH₃COCH₃

C₂H₅OH

CH₃COOH

H₂O

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

Protons and electrons

Electrons and shells

Protons and neutrons

Neutrons and electrons

25. 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

3.2 Na

4.2 Na

Page 2 of 3

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

NO₂

N₂O₃

N₂O

27. Which of the following represents a compound?

A pure substance made up of one type of atom

Two words in one word

Made up of 10 atoms

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

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

Atomic absorption spectrometer

Infra-red spectrometer

Mass spectrometer

Ultraviolet spectrometer

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

H₂O

CC1₄

NaC1

It can be applied to all

30. 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

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

Gain electrons and protons

None of these

Lose electrons

Lose electrons and protons

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

Water

Sodium Chloride

Gold

Soil

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

Fractional distillation technique

Osmosis

Chromatography

Graham’s law of diffusion technique

34. Diameter of an atom is in the range of

2 x10¯¹⁰

0.2 nm

0.2 Pm

0.2 m

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

Protons

Nucleus

Neutrons

Ions

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

Water

Vinegar

Oxygen gas

Air

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

Sugar

Carbon dioxide

Water

Methane

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

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

Moley’s law

Dalton’s law

Hund’s rule

Newton’s law

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

Molecular formula /n = Empirical formula

Empirical formula /n = Molecular formula

Empirical formula x n² = Molecular formula

Empirical formula x √n = Molecular formula

41. 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

86% hydrogen and 14% carbon

14% hydrogen and 86% carbon

83% hydrogen and 17% carbon

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

66.67%

24.51%

32.47%

12.26%

43. The prefix 10¹⁸ is

Exa

Giga

Nano

Kilo

44. What is the net charge on ferrous ion?

45. Which of the following represents an element?

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

A compound made up of one type of element

The periodic table

A pure substance made up of one type of atom

46. 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

47. The modern atomic weight scale is based on

C¹³

O¹⁶

H¹

C¹²

48. 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

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

CuO, Cu₂O

H₂S, SO₂

NH₃, HC1

CS₂, FeSO₄

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

They possess different mass number

They possess same chemical properties

They possess same physical properties

They possess same position in the periodic table

Page 3 of 3

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

MC1₃

MC1

M₂C1₂

MCL₂

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

6.02 x 10²²

3.01 x 10²³

6.02 x 10²³

3.01 x 10²²

53. 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

54. What are the parts of an atom?

Protons, neutrons, nucleus, mass

Nucleus, element, carbon, space

Protons, neutrons, electrons, nucleus

Ions, electrons, neutrons, water

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

10 moles

5 moles

5000 mole

0.005 mole

56. Isotopes differ in the

Number of protons

Number of neutrons

Number of atoms

Number of electrons

57. Which one of the following is ambiguous?

A mole of electrons

A mole of sodium atoms

A mole of potassium ions

A mole of hydrogen

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

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

SO₃

S₂O₃

SO₂

60. 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

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

Al₂O₃

Mg(ClO₄)₂

KOH

SiO₂

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

112 Cm³

22.4 dm³

1.12 dm³

2.24 dm³

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

CH₂O

C₄H₈O₄

C₂H₄O₂

C₃H₆O₃

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

7.31 x 10¯²³

1.99 x 10¯²³

1.37 x 10²²

4.65 x 10¯²³

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

66. What is a chemical compound?

A combination of two protons and two electrons

A combination of two or more chemical elements

A mixture of two or more substance

A subatomic particle

67. Difference in density is the basis of

Molecular attraction

Ultrafiltration

Molecular sieving

Gravity separation

68. What is a multivalent ion?

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

An ion that can have more than one charge

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

To reduce the time for completion of the reaction

To carry out compete combustion

All of these

To reduce the economy of the process

70. 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,

Nm¯²s¯²

Kg m¯¹s¯¹

Nil, it is dimensionless constant

Newton

71. 1 mole of CH₄ contains

3.0 g of carbon

1.81 x 10²³ molecules of CH₄

4 g-atom of hydrogen

6.02 x 10²³ atoms of H

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Maan AliLast Updated: April 19, 2025

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22 Comments

Khudabux mari padidan station says:

June 1, 2022 at 9:06 am

95

Salman Khan says:

August 6, 2021 at 11:10 pm

80%

Muhammad Umair says:

June 22, 2021 at 7:10 am

There are some mistakes in some mcqs answers

Ubaid Nadeem says:

August 25, 2020 at 8:33 pm

The relative atomic mass of chlorine is 35.5. What is the mass of 2 moles of chlorine gas?
chlorine gas has 2 atom so, the mass of two moles of chlorine gas is 142 not 71

Hamza says:

July 29, 2020 at 5:24 am

I will get good marks

Sarah Aimen says:

August 12, 2017 at 6:55 pm

75% 😛

1. MUHAMMAD AWAIS ATTARI says:
  
  July 22, 2020 at 1:34 pm
  
  i am also 75 % marks
  
2. MUHAMMAD AWAIS ATTARI says:
  
  July 22, 2020 at 1:35 pm
  
  reply sarah
  
3. Iqra saleem says:
  
  December 9, 2021 at 10:45 pm
  
  Sir please ap bta skty Hain k ma apni entry test ki tyari Ghar ma rah kr kis tareeky say kr skti ho. Please guide me
  
4. Binte Habib says:
  
  July 29, 2022 at 1:01 pm
  
  Best test for parctice I got 90%
  
sara khalid says:

June 28, 2017 at 5:02 pm

i have got 80 percent marks

Secunder says:

June 24, 2017 at 4:08 am

Ned test is not that hard I guess

1. Iqra saleem says:
  
  December 9, 2021 at 10:47 pm
  
  Apny diya ha test Ned ka
  
iqra ch says:

June 3, 2017 at 9:19 pm

i got a 98% marks

1. Mohsin Jameel says:
  
  August 2, 2022 at 3:50 pm
  
  Nyc good
  
duaa qureshi says:

October 15, 2016 at 1:33 pm

percentage 55% 😀

1. Afaq says:
  
  July 11, 2017 at 9:22 pm
  
  lol that was sooo ez i got 100%
  
2. Hamza says:
  
  July 29, 2020 at 5:26 am
  
  I get 90% marks
  
farman ali says:

August 16, 2016 at 11:20 am

i have got 97 from that test………..

Unknown says:

June 3, 2016 at 12:07 am

A few questions don’t make any sense with their choices, not to mention that broken/wrong answers to them are also there. For instance, the question where 2 moles of Cl2 gas are asked. The answer is 142g however the answer, set by the creator of these tests, is 71g. Apart from that, the test is quite helpful.

1. Bisma pari memon says:
  
  August 6, 2020 at 8:51 pm
  
  I got 90%
  
2. Munaza says:
  
  September 7, 2020 at 11:35 am
  
  I agree

ECAT Chemistry Basic Concepts Test Online

Chemistry Basic Concepts MCQS Online Test

ECAT Chemistry Basic Concepts Chapter Online Test

ECAT Chemistry Basic Concepts Test

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Maan Ali

22 Comments

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Chemistry Basic Concepts MCQS Online Test

ECAT Chemistry Basic Concepts Chapter Online Test

ECAT Chemistry Basic Concepts Test

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Maan Ali

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