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

S₂O₃

SO₂

SO₃

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

Sodium Chloride

Soil

Water

Gold

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

Methane

Carbon dioxide

Sugar

Water

4. 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

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

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

Combustion method

K. Jeldahl’s method

All of above

Duma’s method

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

Element

Compound

Mixture

Crystal

8. What are the two different types of ions?

Negative and positive

Polyatomic and multivalent

Polyatomic and compound ions

Electrons and protons

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

N₂O

NO₂

N₂O₃

10. 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

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

Hund’s rule

Moley’s law

Newton’s law

Dalton’s law

12. 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

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

0.90

0.11

1.11

1.0

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

5 moles

10 moles

5000 mole

0.005 mole

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

2.4 Na

4.2 Na

3.2 Na

1.6 Na

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

66.67%

32.47%

12.26%

24.51%

17. 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

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

C₆H₁₂O₆

BaO₂

C₂H₄

H₂O₂

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

2, 2, 1, 1, 1

2, 1, 1, 2, 1

2, 2, 1, 2, 1

1, 1, 2, 2, 1

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

22.4 dm³

2.24 dm³

112 Cm³

1.12 dm³

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

MCL₂

MC1₃

M₂C1₂

MC1

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

To reduce the time for completion of the reaction

To reduce the economy of the process

All of these

To carry out compete combustion

23. 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

24. What is the net charge on ferrous ion?

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

NH₃, HC1

CuO, Cu₂O

CS₂, FeSO₄

H₂S, SO₂

Page 2 of 3

26. What is a chemical compound?

A mixture of two or more substance

A subatomic particle

A combination of two protons and two electrons

A combination of two or more chemical elements

27. Percent of calcium in calcium carbonate is

20%

30%

80%

40%

28. 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

Newton

Nm¯²s¯²

Kg m¯¹s¯¹

29. 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

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

Air

Vinegar

Water

Oxygen gas

31. 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

32. Difference in density is the basis of

Ultrafiltration

Gravity separation

Molecular sieving

Molecular attraction

33. 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

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

CH₂O

C₄H₈O₄

C₃H₆O₃

C₂H₄O₂

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

14% hydrogen and 86% carbon

17% hydrogen and 83% carbon

83% hydrogen and 17% carbon

86% hydrogen and 14% carbon

36. 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

Cu₂Cl₃

CuCl₂

37. The prefix 10¹⁸ is

Kilo

Exa

Giga

Nano

38. Diameter of an atom is in the range of

2 x10¯¹⁰

0.2 m

0.2 nm

0.2 Pm

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

Ionic charges

Ionic atoms

Ionic compounds

Ionic element

40. 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

1:1:1

1:16:2

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

6 x 10²²

12 x 10²³

1.2 x 10²³

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

Electrons and shells

Protons and neutrons

Protons and electrons

Neutrons and electrons

43. 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

Stoichiometric calculation can only be done if no side reaction happen

A limiting reactant is used at the end of reaction

44. 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%

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

Graham’s law of diffusion technique

Osmosis

Fractional distillation technique

Chromatography

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

None of these

Gain electrons and protons

Lose electrons and protons

Lose electrons

47. Which of the following represents an element?

A pure substance made up of one type of atom

A compound made up of one type of element

The periodic table

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

48. What is a multivalent ion?

Some ions can have only one charge

Only negatively charged

An ion that can have more than one charge

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

49. 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

50. Isotopes differ in the

Number of neutrons

Number of protons

Number of atoms

Number of electrons

Page 3 of 3

51. 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 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.

52. 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

53. The percentage of oxygen in NaOH is

54. 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

Definite proportions

Constant volume

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

SiO₂

Al₂O₃

KOH

Mg(ClO₄)₂

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

It can be applied to all

CC1₄

NaC1

H₂O

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

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

59. 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 3 atoms

3 elements and a total of 2 atoms

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

1.00

0.5

0.75

0.25

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

6.02 x 10²³ x 2

6.02 x 10²³

3 x 6.02 x 10²³

4 x 6.02 x 10²³

62. 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

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

Nucleus

Protons

Neutrons

Ions

64. Which of the following is an element?

Water

Common Salt

Gold

Sugar

65. Empirical formula of chloroform is

CHCl₃

CH₂C₁₂

CHCl

CH₃cl

66. 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

67. The compound having highest percent of oxygen is

H₂O

CH₃COOH

CH₃COCH₃

C₂H₅OH

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

4.65 x 10¯²³

7.31 x 10¯²³

1.37 x 10²²

1.99 x 10¯²³

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

Chromatography

Sublimation

Crystallization

Graham’s Law of diffusion

70. What are the parts of an atom?

Nucleus, element, carbon, space

Protons, neutrons, nucleus, mass

Protons, neutrons, electrons, nucleus

Ions, electrons, neutrons, water

71. The modern atomic weight scale is based on

C¹²

O¹⁶

C¹³

H¹

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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

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