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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. 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

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

Empirical formula x n² = Molecular formula

Molecular formula /n = Empirical formula

Empirical formula /n = Molecular formula

Empirical formula x √n = Molecular formula

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

Chromatography

Graham’s law of diffusion technique

Osmosis

Fractional distillation technique

4. 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

Nil, it is dimensionless constant

Newton

Kg m¯¹s¯¹

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

0.25

0.5

0.75

1.00

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

7. Indicate the incorrect statement form the following

Actual yield is always less than theoretical yield

Stoichiometric calculation can only be done if no side reaction happen

A limiting reactant is used at the end of reaction

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

8. What is a multivalent ion?

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

Some ions can have only one charge

Only negatively charged

An ion that can have more than one charge

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

0.90

0.11

1.0

1.11

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

3.01 x 10²²

6.02 x 10²³

6.02 x 10²²

3.01 x 10²³

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

H₂S, SO₂

CS₂, FeSO₄

CuO, Cu₂O

NH₃, HC1

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

The atomic mass plus the number of electrons

The atomic mass subtracted the number of protons

The atomic mass subtracted the number of electrons

The atomic mass plus the number of protons

13. Percent of calcium in calcium carbonate is

30%

80%

40%

20%

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

KOH

Mg(ClO₄)₂

Al₂O₃

SiO₂

15. Empirical formula of chloroform is

CH₂C₁₂

CHCl

CH₃cl

CHCl₃

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

66.67%

24.51%

12.26%

32.47%

17. 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

18. Isotopes differ in the

Number of atoms

Number of protons

Number of neutrons

Number of electrons

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

Nucleus

Neutrons

Protons

Ions

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

2 elements and a total of 3 atoms

3 elements and a total of 2 atoms

3 elements and a total of 3 atoms

2 elements and a total of 2 atoms

21. 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

22. 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

23. 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

CuCl₃

Cu₂Cl₃

CuCl

24. What are the parts of an atom?

Protons, neutrons, electrons, nucleus

Nucleus, element, carbon, space

Protons, neutrons, nucleus, mass

Ions, electrons, neutrons, water

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

Dalton’s law

Hund’s rule

Moley’s law

Newton’s law

Page 2 of 3

26. 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

A pure substance made up of one type of atom

The periodic table

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

MC1

MC1₃

M₂C1₂

MCL₂

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

29. 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

Constant volume

Multiple proportions

Conservation of mass

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

S₂O₃

SO₂

SO₃

31. 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

14% hydrogen and 86% carbon

86% hydrogen and 14% carbon

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

Water

Gold

Sodium Chloride

Soil

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

4.65 x 10¯²³

7.31 x 10¯²³

1.99 x 10¯²³

1.37 x 10²²

34. What are the two different types of ions?

Polyatomic and multivalent

Polyatomic and compound ions

Negative and positive

Electrons and protons

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

20.05%

80.03%

19.97%

50%

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

37. Which of the following is an element?

Water

Sugar

Gold

Common Salt

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

4 x 6.02 x 10²³

6.02 x 10²³ x 2

3 x 6.02 x 10²³

6.02 x 10²³

39. 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

40. The compound having highest percent of oxygen is

CH₃COCH₃

H₂O

C₂H₅OH

CH₃COOH

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

Crystal

Mixture

Element

Compound

42. 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

43. What is a chemical compound?

A combination of two or more chemical elements

A mixture of two or more substance

A subatomic particle

A combination of two protons and two electrons

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

Ionic element

Ionic atoms

Ionic charges

Ionic compounds

45. 1 mole of CH₄ contains

4 g-atom of hydrogen

1.81 x 10²³ molecules of CH₄

6.02 x 10²³ atoms of H

3.0 g of carbon

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

0.0704

0.0233

0.0732

0.210

47. Difference in density is the basis of

Ultrafiltration

Molecular sieving

Gravity separation

Molecular attraction

48. The prefix 10¹⁸ is

Exa

Kilo

Nano

Giga

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

2.4 Na

1.6 Na

3.2 Na

4.2 Na

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

Mass spectrometer

Infra-red spectrometer

Ultraviolet spectrometer

Atomic absorption spectrometer

Page 3 of 3

51. What is the net charge on ferrous ion?

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

22.4 dm³

1.12 dm³

112 Cm³

2.24 dm³

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

Matter always consists of molecules

Matter is always composed of atoms

All matter contains chemical elements

All substances are made of matter

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

H₂O₂

BaO₂

C₂H₄

C₆H₁₂O₆

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

N₂O₃

NO₂

N₂O

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

12 x 10²³

1.2 x 10²³

6 x 10²²

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

NaC1

H₂O

It can be applied to all

CC1₄

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

Protons and electrons

Protons and neutrons

Neutrons and electrons

Electrons and shells

59. Which one of the following is ambiguous?

A mole of potassium ions

A mole of sodium atoms

A mole of hydrogen

A mole of electrons

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

Chromatography

Sublimation

Crystallization

Graham’s Law of diffusion

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

All of these

To carry out compete combustion

To reduce the economy of the process

To reduce the time for completion of the reaction

62. 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

2:16:2

1:16:2

2:16:1

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

C₂H₄O₂

C₄H₈O₄

C₃H₆O₃

CH₂O

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

They possess different mass number

They possess same chemical properties

They possess same position in the periodic table

They possess same physical properties

65. The modern atomic weight scale is based on

O¹⁶

C¹²

H¹

C¹³

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

Gain electrons and protons

None of these

Lose electrons and protons

Lose electrons

67. Diameter of an atom is in the range of

0.2 m

0.2 nm

0.2 Pm

2 x10¯¹⁰

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

5000 mole

0.005 mole

5 moles

10 moles

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

Air

Oxygen gas

Vinegar

Water

70. 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.

71. The percentage of oxygen in NaOH is

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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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