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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. Diameter of an atom is in the range of

2 x10¯¹⁰

0.2 m

0.2 Pm

0.2 nm

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

Carbon dioxide

Sugar

Methane

Water

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

4. 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.

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

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

1.99 x 10¯²³

7.31 x 10¯²³

1.37 x 10²²

4.65 x 10¯²³

6. 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

7. The modern atomic weight scale is based on

H¹

C¹²

O¹⁶

C¹³

8. The compound having highest percent of oxygen is

C₂H₅OH

CH₃COCH₃

CH₃COOH

H₂O

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

14% hydrogen and 86% carbon

83% hydrogen and 17% carbon

17% hydrogen and 83% carbon

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

H₂O₂

C₂H₄

C₆H₁₂O₆

BaO₂

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

Sodium Chloride

Soil

Gold

Water

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

Al₂O₃

SiO₂

Mg(ClO₄)₂

KOH

13. Empirical formula of chloroform is

CH₃cl

CH₂C₁₂

CHCl

CHCl₃

14. 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 electrons

The atomic mass subtracted the number of protons

The atomic mass plus the number of protons

15. Which one of the following is ambiguous?

A mole of sodium atoms

A mole of potassium ions

A mole of electrons

A mole of hydrogen

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

To carry out compete combustion

To reduce the economy of the process

To reduce the time for completion of the reaction

All of these

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

MC1

MCL₂

M₂C1₂

MC1₃

18. 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

1:1:1

1:16:2

2:16:2

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

SO₂

SO₃

S₂O₃

20. 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

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

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

Crystal

Element

Mixture

Compound

23. 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

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

25. 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

Page 2 of 3

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

0.005 mole

5 moles

10 moles

5000 mole

27. The prefix 10¹⁸ is

Nano

Exa

Kilo

Giga

28. What is a multivalent ion?

An ion that can have more than one charge

Some ions can have only one charge

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

Only negatively charged

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

Hund’s rule

Moley’s law

Dalton’s law

Newton’s law

30. What is the net charge on ferrous ion?

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

Neutrons

Nucleus

Ions

Protons

32. What is a chemical compound?

A combination of two protons and two electrons

A mixture of two or more substance

A subatomic particle

A combination of two or more chemical elements

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

66.67%

24.51%

32.47%

12.26%

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

0.0704

0.210

0.0732

0.0233

35. 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

36. Isotopes differ in the

Number of electrons

Number of atoms

Number of protons

Number of neutrons

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

Fractional distillation technique

Graham’s law of diffusion technique

Osmosis

Chromatography

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

0.90

1.0

1.11

0.11

39. Difference in density is the basis of

Molecular sieving

Molecular attraction

Ultrafiltration

Gravity separation

40. Indicate the incorrect statement form the following

A limiting reactant is used at the end of reaction

Stoichiometric calculation can only be done if no side reaction happen

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

Actual yield is always less than theoretical yield

41. 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

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

3.01 x 10²³

6.02 x 10²³

3.01 x 10²²

6.02 x 10²²

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

Electrons and shells

Neutrons and electrons

Protons and electrons

Protons and neutrons

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

N₂O₃

N₂O

NO₂

45. Which of the following represents an element?

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

The periodic table

46. The percentage of oxygen in NaOH is

47. What are the parts of an atom?

Protons, neutrons, electrons, nucleus

Ions, electrons, neutrons, water

Nucleus, element, carbon, space

Protons, neutrons, nucleus, mass

48. 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

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

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

Air

Oxygen gas

Water

Vinegar

Page 3 of 3

51. Which of the following is an element?

Sugar

Gold

Common Salt

Water

52. 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

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

Chromatography

Sublimation

Crystallization

Graham’s Law of diffusion

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

0.5

0.25

0.75

1.00

55. 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

1.6 Na

3.2 Na

56. 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%

20.05%

19.97%

57. 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

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

CS₂, FeSO₄

NH₃, HC1

CuO, Cu₂O

H₂S, SO₂

59. 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

Multiple proportions

Constant volume

Conservation of mass

Definite proportions

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

H₂O

NaC1

CC1₄

It can be applied to all

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

They possess same chemical properties

They possess different mass number

They possess same position in the periodic table

They possess same physical properties

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

Lose electrons

Lose electrons and protons

Gain electrons and protons

None of these

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

12 x 10²³

6 x 10²²

1.2 x 10²³

64. Which of the following represents a compound?

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

A pure substance made up of one type of atom

Two words in one word

Made up of 10 atoms

65. 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?

CuCl

Cu₂Cl₃

CuCl₂

CuCl₃

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

112 Cm³

1.12 dm³

2.24 dm³

22.4 dm³

67. 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

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

K. Jeldahl’s method

Combustion method

All of above

Duma’s method

69. Percent of calcium in calcium carbonate is

20%

30%

40%

80%

70. 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

71. What are the two different types of ions?

Polyatomic and multivalent

Polyatomic and compound ions

Electrons and protons

Negative and positive

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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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