NEET Foundation Chemistry Chapter 3 Atoms And Molecules Multiple Choice Questions

Chapter 3 Atoms And Molecules Multiple Choice Question And Answers

Direction: Choose the correct option for each questions. There is only one correct response for each question.

Question 1. Who was the first Indian Philosopher who had postulated that matter is divisible?

1. Maharshi Kanad
2. Chanakya
3. Swami Vivekanada
4. Sarvapalli Radhakrishnan

Answer. 1. Maharshi Kanad

Question 2. Why is the symbol of silver written as Ag?

1. The symbol of silver is derived from the French name ‘Agiol’.
2. The symbol of silver is derived from the French name ‘Aglae’.
3. The symbol of silver is derived from the Latin name ‘Argentum’.
4. The symbol of silver is derived from the German name ‘Agapios’.

Answer. 3. The symbol of silver is derived from the Latin name ‘Argentum’.

Question 3. What do you mean by atomicity of a molecule?

1. The number of molecules in a substance.
2. The number of atoms present in one molecule of a substance.
3. The number of atoms bonded in a molecule of an element.
4. The mass of an atom of an element.

Answer. 2. The number of atoms present in one molecule of a substance.

Read and Learn More NEET Foundation Multiple Choice Questions

Question 4. What do you mean by saying that molecular mass of oxygen is 32?

1. 1/1837 times the mass of proton.
2. Molecule of O₂ is 32 times heavier as compared to 1/12th of the mass of an atom of C-12 isotope.
3. Molecule of O₂ is 8 times heavier as compared to 1/12th of the mass of an atom of C-12 isotope.
4. None of the above

Answer. 2. Molecule of O₂ is 32 times heavier as compared to 1/12th of the mass of an atom of C-12 isotope.

Question 5. If 100 g of calcium carbonate on heating produces 44 g of carbon dioxide, how much quick lime will be formed?

1. Quick lime will be 56 g
2. Quick lime will be 72 g
3. Quick lime will be 38 g
4. Quick lime will be 44 g

Answer. 1. Quick lime will be 56 g

Question 6. What was the postulate of Dalton’s atomic theory about the masses of atom?

1. Atoms of an element have same mass.
2. Atoms of an element have less mass.
3. Atoms of all substances are identical in all respects.
4. Atoms are divisible particles.

Answer. 1. Atoms of an element have same mass.

Question 7. What is atomic mass unit u?

1. 1/6 of the mass of an atom of C-12 isotope.
2. 1/2 of the mass of an atom of C-12 isotope.
3. 1/12 of the mass of an atom of C-12 isotope.
4. None of these

Answer. 3. 1/12 of the mass of an atom of C-12 isotope.

Question 8. Which of the following is not correct according to Dalton’s atomic theory?

1. Matter is made up of atoms.
2. Atoms of all substances are identical in all respects.
3. Atoms combined in a simple whole number ratio.
4. Atoms of two elements can combine to form more than one compound.

Answer. 2. Atoms of all substances are identical in all respects.

Question 9. Which of the following represents 1 u?

1. Mass of C-12 atom
2. Mass of O-16 atom
3. 1/12 of mass of C-12 atom
4. Mass of hydrogen molecule

Answer. 3. 1/12 of mass of C-12 atom

Question 10. Who formulated the law of constant composition?

1. Dalton
2. Proust
3. Lavoisier
4. Berzelius

Answer. 2. Proust

Question 11. What is the molecule C₆₀ called?

1. C₆₀ is called Atomic number.
2. C₆₀ is called Isobar.
3. C₆₀ is called hydrogen bond.
4. C₆₀ is called Buckminster fullerene.

Answer. 4. C₆₀ is called Buckminster fullerene.

Question 12. Why the atomic masses are not the actual masses of atom?

1. Atoms are very small particles therefore their actual masses are too small to be determined.
2. Atoms combined in a simple whole number ratio.
3. A group of atoms carrying a positive charge.
4. None of these

Answer. 1. Atoms are very small particles therefore their actual masses are too small to be determined.

Question 13. Calculate the formula unit mass of Na₂CO₃ ⋅ 10H₂O.

Atomic masses: Na = 23.0 u, C = 12.0 u, O = 16.0 u, H = 1.0 u.

1. 390 u
2. 288 u
3. 286 u
4. 199 u

Answer. 3. 286 u

Question 14. One of the following molecule has an atomic of four

1. H₂O
2. NH₃
3. CH₄
4. CO₂

Answer. 2. NH₃

Question 15. Why is atomic mass taken as average value?

1. The mass of 1 mole of the substance is molar mass of that substance.
2. An element may have atoms with different masses present in a definite ratio.
3. Atoms are very small particles; their actual masses are too small to be determined.
4. All of above

Answer. 2. An element may have atoms with different masses present in a definite ratio.

Question 16. What is the actual mass of an atom of C-12 isotope?

1. 0.990 × 10^-23 g
2. 1.993 × 10^-23 g
3. 1.992 × 10^-23 g
4. 2.857 × 10^-23 g

Answer. 3. 1.992 × 10^-23 g

Question 17. Hydrogen was passed over heated 2 g copper oxide till only copper was left. The mass of copper obtained was 1.6 g. The percentage of oxygen in copper oxide is

1. 80%
2. 60%
3. 40%
4. 20%

Answer. 4. 20%

Question 18. Give one example of the molecule of a triatomic element.

1. O₃
2. P₃
3. NH₃
4. P₄

Answer. 1. O₃

Question 19. Which of the following is the correct symbol for copper?

1. Co
2. Cr
3. Cu
4. Cp

Answer. 3. Cu

Question 20. The formula of copper sulphate is CuSO₄. What is the valency of copper if the valency of SO₄ is 2?

1. 1
2. 3
3. 2
4. 4

Answer. 3. 2

Question 21. In a sample of ammonia the mass ratio of nitrogen and hydrogen is 14:1. Find the ratio of N and H atoms in a molecule of ammonia. Relative atomic masses are: H = 1, N = 14.

1. In ammonia the ratio by number of atoms = N:H = 2:3
2. In ammonia the ratio by number of atoms = N:H = 1:3
3. In ammonia the ratio by number of atoms = N:H = 1:14
4. In ammonia the ratio by number of atoms = N:H = 1:4

Answer. 2. In ammonia the ratio by number of atoms = N:H = 1:3

Question 22. Hydrogen and oxygen combine in the mass ratio of 1:8 to form water. Calculate the mass of oxygen gas required to react completely with 3 g of hydrogen.

1. 24 g
2. 26 g
3. 32 g
4. 18 g

Answer. 1. 24 g

Question 23. What are the valencies of Al and carbonate in Al₂(CO₃)₃?

1. Aluminium is 3 and carbonate is 1
2. Aluminium is 1 and carbonate is 2
3. Aluminium is 3 and carbonate is 3
4. Aluminium is 3 and carbonate is 2

Answer. 4. Aluminium is 3 and carbonate is 2

Question 24. Which one of the following is equal to one mole of N₂?

1. 14 g of nitrogen
2. 20 grams of nitrogen
3. 6.022 × 10²³ N₂ molecules
4. All the three

Answer. 3. 6.022 × 10²³ N₂ molecules

Question 25. How was the postulate of Dalton’s atomic theory about the masses of atoms modified?

1. Matter is made up of small particles which may be atoms or molecules.
2. Atoms Mass can neither be created nor destroyed in a chemical reaction.
3. Atoms of the same or different elements combine together to form molecules or compounds.
4. Atoms of the same element may have different masses.

Answer. 4. Atoms of the same element may have different masses.

Question 26. Why has the symbol ‘u’ been replaced by ‘u’?

1. Atomic mass unit is 1/12th of the mass of an atom of C-12 isotope.
2. Atoms of an element have same mass.
3. To avoid an ambiguity whether to take O-16 as the reference or average mass of isotopes of O-atoms.
4. None of the above

Answer. 3. To avoid an ambiguity whether to take O-16 as the reference or average mass of isotopes of O-atoms.

Question 27. What do you understand by Gram Molar Volume?

1. Volume occupied by one mole of the substance.
2. Volume occupied by whole substance.
3. Those compounds which are made up of only two elements.
4. None of the three.

Answer. 1. Volume occupied by one mole of the substance.

Question 28. What is Avogadro’s number?

1. The volume of the substance present in one mole of the substance.
2. The number of particles of the substance present in one mole of the substance.
3. It is defined as the units of positive or negative charge present on the ion.
4. Molecular mass expressed in grams.

Answer. 2. The number of particles of the substance present in one mole of the substance.

Question 29. What do you understand by polyatomic cation?

1. A group of atoms carrying a positive charge.
2. A group of atoms carrying a negative charge.
3. A group of atoms carrying both the charges.
4. A group of atoms carrying neither positive charge nor negative charge.

Answer. 1. A group of atoms carrying a positive charge.

Question 30. How do you define mole in terms of mass?

1. The sum of the atomic masses of all the atoms present in one unit of compound.
2. Amount of the substance which has volume equal to 22400 mL at STP conditions.
3. A mole of a substance is equal to the gram atomic mass of the substance.
4. None of these

Answer. 3. A mole of a substance is equal to the gram atomic mass of the substance.

Question 31. Which of the following has maximum number of atoms?

1. 18 g H₂O
2. 18 g of CH₄
3. 18 g of O₂
4. 18 g of CO₂

Answer. 2. 18 g of CH₄

Question 32. Which of the following would weigh the highest?

1. 10 moles of H₂O
2. 0.2 mole of sucrose (C₁₂ H₂₂ O₁₁)
3. 2 moles of CaCO₃
4. 2 moles of CO₂

Answer. 3. 2 moles of CaCO₃

Question 33. A change in the physical state can be brought about

1. Only when energy is given to the system.
2. Only when energy is taken out from the system.
3. When energy is either given to, or taken out from the system.
4. Without any energy change.

Answer. 3. When energy is either given to, or taken out from the system.

Question 34. Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic mass of magnesium is 24 g mol(raise to the power –1).

1. 0.5 mole
2. 1 mole
3. 1.5 mole
4. 2 mole

Answer. 1. 0.5 mole

Question 35. How do you define the valency of an element in a molecular compound?

(1) It’s combining capacity and is equal to the number of hydrogen atoms.

(2) Number of chlorine atoms.

(3) Ratio of molar should be equal.

(4) Double the number of oxygen atoms with

which one atom of the element combines.

1. (1), (2) and (4)
2. (1) and (3)
3. (2) and (4)
4. (1) and (2)

Answer. 1. (1), (2) and (4)

Question 36. One mole of CO₂ means

(1) 6.022 × 10²³ molecules of CO₂

(2) 22.4 L at STP

(3) 44 g of CO₂

(4) 55 g of C

1. (1) and (2)
2. (1) and (3)
3. (2) and (4)
4. (1), (2) and (3)

Answer. 4. (1), (2) and (3)

Question 37. The Scientist Proust established which of the below mentioned law in the year 1779?

(1) In a chemical substance its constituent elements are present in definite proportions by mass.

(2) A pure compound has a definite composition by mass of its constituent elements.

(3) It is not possible to create or destroy the mass of a substance by chemical reactions.

(4) Atoms combine in whole numbers.

1. (1), (2) and (4)
2. (2) and (3)
3. (1) and (2)
4. All of the above

Answer. 3. (1) and (2)

Question 38. Which of the following are incorrect?

(1) Atoms are divisible particles.

(2) Atoms can be created or destroyed during a chemical reaction and all matter is made up of atoms.

(3) Mass of matter is due to the mass of atoms which constitute it.

(4) Atom and mass are not conserved.

1. (2) and (4)
2. (1), (2) and (3)
3. (1), (2) and (4)
4. All of the above

Answer. 3. (1), (2) and (4)

Question 39. Which of the following are monoatomic metallic elements?

(1) Sodium Na

(2) Copper Cu

(3) Aluminium Al

(4) All of above

1. (4)
2. (2) and (3)
3. (1)
4. None of the above

Answer. 1. (4)

Question 40. Which of the following statement about polyatomic ions are correct?

(1) A group of two or more atoms carrying a charge is called polyatomic ion.

(2) A polyatomic cation carries a charge.

(3) A polyatomic anion carries a negative charge.

(4) A polyatomic cation does not carry a charge

1. (1), (3) and (4)
2. (3) and (4)
3. (1) and (4)
4. (1), (2) and (3)

Answer. 4. (1), (2) and (3)

Question 41. Which of the following are the correct options?

(1) Law of conservation of mass is the law of indestructibility of matter.

(2) Atoms masses are the average relative masses of the atoms.

(3) Atoms may or may not be capable of free existence but molecules can always exist freely.

(4) A group of atoms carrying both the charges.

1. (2) and (3)
2. (1), (2) and (3)
3. (1) and (3)
4. (2) and (4)

Answer. 2. (1), (2) and (3)

Question 42. Which of the following support modified Dalton’s Atomic theory?

(1) It is not possible to create or destroy the mass of a substance by chemical reactions.

(2) Atoms of the same element have same chemical properties but they may have different physical properties.

(3) Atoms of an element have the same mass was proved wrong when it was found that an element may exist in atoms with different masses, e.g., chlorine atoms with masses 35 and 37 etc.

1. (2) and (3)
2. (1)
3. (1) and (3)
4. None of the above

Answer. 1. (2) and (3)

Question 43. Which of the following symbols of elements are incorrect?

(1) Cobalt Co

(2) Aluminium Al

(3) Carbon C

(4) Helium He

1. (1), (3) and (4)
2. (2), (3) and (4)
3. (1), (2) and (3)
4. All of above

Answer. 3. (1), (2) and (3)

Question 44. Which of the following correctly represents 360 g of water?

(1) 2 mole of H₂O

(2) 20 moles of water

(3) 6.20 × 10²³ molecules of water

(4) 1.2044 × 10²⁵ molecules of water

1. (1) and (4)
2. (2) and (4)
3. (1) and (3)
4. (3) and (2)

Answer. 2. (2) and (4)

Question 45. Calculate the mass of 1 mol of N atoms?

1. 14 g
2. 13 g
3. 15 g
4. None of these

Answer. 1. 14 g

Question 46. The smallest particle of matter which can exist independently is

1. an atom
2. a molecule
3. an ion
4. a radical

Answer. 2. a molecule

Question 47. Match the following;

(1) Sodium chloride (a) NaI

(2) Sodium bromide (b) NaCl

(3) Sodium iodide (c) NaBr

1. (1) – A, (2) – C, (3) – B
2. (1) – C, (2) – B, (3) – A
3. (1) – B, (2) – C, (3) – A
4. (1) – A, (2) – B, (3) – C

Answer. 3. (1) – B, (2) – C, (3) – A

Question 48. The relative molecular mass of copper (2) sulphate, CuSO₄ is 160 and the relative molecular mass of water is 18. The percentage by mass of water in copper (2) sulphate crystals, CuSO₄.5H₂O is

1. \(\frac{18}{160} \times 100\)
2. \(\frac{5 \times 18}{160} \times 100\)
3. \(\frac{5 \times 18}{(160+18)} \times 100\)
4. \(\frac{5 \times 18 \times 100}{160+(5 \times 18)}\)

Answer. 4. \(\frac{5 \times 18 \times 100}{160+(5 \times 18)}\)

Question 49. Calculate the number of particles in 0.1 moles of carbon atoms?

1. 6.022 × 10²³
2. 6.022 × 10²²
3. 6.021 × 10²¹
4. None of these

Answer. 2. 6.022 × 10²²

Question 50. Which of the following ammonium salts will liberate the greatest amount of ammonia on heating?

1. 1 mole of (NH4)₃PO₄
2. 1 mole of (NH4)₂SO₄
3. 1 mole of NH₄Cl
4. 1 mole of NH₄NO₃

Answer. 1. 1 mole of (NH4)₃PO₄

Question 51. Calculate the mass of 3.011 × 10²³ number of atoms of N?

1. 7 g
2. 7.5 g
3. 6 g
4. None of these

Answer. 1. 7 g

Question 52. The anion present in calcium hydride is

1. H⁺
2. H^–
3. OH^–
4. H3O⁺

Answer. 2. H^–

Question 53. The gas which has a molecular mass twice that of oxygen gas is

1. CO₂
2. CO
3. SO₂
4. H₂S

Answer. 3. SO₂

Question 54. The element which can form gases having two different atomicities is

1. chlorine
2. oxygen
3. hydrogen
4. nitrogen

Answer. 4. nitrogen

Question 55. Which of the following is a correct formula of the calcium carbonate?

1. CaO
2. CaCO₂
3. CaCO₃
4. None of these

Answer. 3. CaCO₃

Question 56. The element which loses electrons to form ions with variable valencies is

1. copper
2. silver
3. mercury
4. all the above

Answer. 4. all the above

Question 57. The number of elements which are present in the compound ammonium phosphate is

1. 2
2. 3
3. 4
4. 5

Answer. 3. 4

Question 58. Ratio by mass of the element present in SO₂ is

1. 1: 1
2. 1: 2
3. 2: 1
4. 3: 1

Answer. 1. 1: 1

Question 59. A plumbous ion is formed from lead atom by

1. gaining one electron
2. gaining two electrons
3. losing one electron
4. losing two electrons

Answer. 4. losing two electrons

Question 60. Which of the following is a correct formula of the copper nitrate?

1. Cu (NO₃)₂
2. NaNO₃
3. Mg (NO₃)₂
4. None of these

Answer. 1. Cu (NO₃)₂

Question 61. The acid which does not contain a radical of a polyatomic group is

1. sulphuric acid
2. hydrochloric acid
3. nitric acid
4. phosphoric acid

Answer. 2. hydrochloric acid

Question 62. If the nitride of a metal M has the formula MN, what is the formula of its sulphide, carbonate and chloride?

1. M₂S₃, M₂(CO₃)₃, MCl
2. MS₃, M₂CO₃, MCl₃
3. MS, M(CO₃)₃, MCl
4. M₂S₃, M₂(CO₃)₃, MCl₃

Answer. 4. M₂S₃, M₂(CO₃)₃, MCl₃

Question 63. According to the IUPAC recommendation “amu” has been replaced with “u”. “u” stands for

1. universal mass
2. ultimate mass
3. unified mass
4. unending mass

Answer. 3. unified mass

Question 64. Which of the following information is not conveyed by a chemical equation?

1. The reactants taking part in the reaction
2. The products formed in the reaction
3. The speed of the reaction
4. The ratio of the weights of reactants and products taking part in the reaction

Answer. 3. The speed of the reaction

Question 65. What are the values of the coefficients x, y and z in the following reaction?

x Mg + y N2 → z Mg3N2

1. x = 1, y = 1, z = 1
2. x = 1, y = 3, z = 1
3. x = 1, y = 2, z = 1
4. x = 3, y = 1, z = 1

Answer. 4. x = 3, y = 1, z = 1

Question 66. Elements X and Y react to form X_a Y_b. Elements P and Q react to form P_m Q_n. The formula of the compound formed between X and Q is

1. X_bQ_m
2. X_mQ_b
3. X_aQ_n
4. X_nQ_a

Answer. 2. X_mQ_b

Question 67. 0.66 g of a hydrocarbon gave 1.32 g of carbon dioxide and 2.7 g of water on complete combustion. Which law of chemical combination does this example illustrate?

1. Law of conservation of mass
2. Law of constant proportions
3. Both (a) and (b)
4. None of the above

Answer. 1. Law of conservation of mass

Question 68. The ratio of the number of moles of copper, oxygen and copper (2) oxide in the reaction

Copper + Oxygen → Copper (2) oxide is

1. 1: 1: 1
2. 1: 2: 1
3. 2: 1: 2
4. 2: 2: 1

Answer. 3. 2: 1: 2

Question 69. An anion has

1. more electrons than protons
2. more protons than electrons
3. more neutrons than protons
4. more protons than neutrons

Answer. 1. more electrons than protons

Question 70. Atomic number of an element X is 9. Which of the following represents the correct equation for the ion formation of an atom of X?

1. X – e^– → X^–
2. X + e^–→ X^–
3. X – e^– →X⁺
4. X + e^– → X⁺

Answer. 2. X + e^–→ X^–

Question 71. An atom of X combines with 2 atoms of hydrogen. The valency of X is

1. 1
2. 2
3. 3
4. 4

Answer. 2. 2

Question 72. An element has 10 electrons in it atom. How many electrons are gained by the atom of the element to form an anion?

1. 1
2. 2
3. 3
4. zero

Answer. 4. zero

Question 73. Identify the incorrect statement.

1. Molecular weight is equal to the sum of the atomic weights of the elements present in a compound.
2. The composition by weight of the elements in a compound is known from the chemical formula.A chemical formula gives the number of atoms of each element present in one molecule of a compound.
3. Molecular formula of a compound represents one atom of the compound.

Answer. 4. Molecular formula of a compound represents one atom of the compound.

Question 74. The number of Ca²⁺ and Cl^– ions in 222 g anhydrous CaCl₂ is

1. N₀ ions of both Ca²⁺ and Cl^–
2. 4N₀ ions of Ca²⁺, 2N0 ions of Cl^–
3. 2N₀ ions of Ca²⁺, 4N0 ions of Cl^–
4. 2N₀ ions of Ca²⁺ and Cl^–

Answer. 3. 2N0 ions of Ca²⁺, 4N₀ ions of Cl^–

Question 75. Which of the following correctly represents 360 g of water?

(1) 2 moles of H₂O

(2) 20 moles of water

(3) 6.022 × 10²³ molecules of water

(4) 1.2044×10²⁵ molecules of water

1. (1)
2. (1) and (4)
3. (2) and (3)
4. (2) and (4)

Answer. 4. (2) and (4)

Question 76. Which of the following statements is not true about an atom?

1. Atoms are not able to exist independently
2. Atoms are the basic units from which molecules and ions are formed
3. Atoms are always neutral in nature
4. Atoms aggregate in large numbers to form the matter that we can see,feel or touch

Answer. 1. Atoms are not able to exist independently

Question 77. The chemical symbol for nitrogen gas is

1. Ni
2. N₂
3. N⁺
4. N

Answer. 2. N₂

Question 78. The chemical symbol for sodium is

1. So
2. Sd
3. NA
4. Na

Answer. 4. Na

Question 79. Which of the following would weigh the highest?

1. 0.2 mole of sucrose (C₁₂ H₂₂ O₁₁)
2. 2 moles of CO₂
3. 2 moles of CaCO₃
4. 10 moles of H₂O

Answer. 3. 2 moles of CaCO₃

Question 80. Which of the following has maximum number of atoms?

1. 18 g of H₂O
2. 18 g of O₂
3. 18 g of CO₂
4. 18 g of CH₄

Answer. 4. 18 g of CH₄

Question 81. Which of the following contains maximum number of molecules?

1. 1 g CO₂
2. 1 g N₂
3. 1 g H₂
4. 1 g CH₄

Answer. 3. 1 g H₂

Question 82. Mass of one atom of oxygen is

1. \(\frac{16}{6.023 \times 10^{23}} 8\)
2. \(\frac{32}{6.023 \times 10^{23}} g\)
3. \(\frac{1}{6.023 \times 10^{23}} g\)
4. 8 u

Answer. 1. \(\frac{16}{6.023 \times 10^{23}} 8\)

Question 83. 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are

1. 6.68 × 10²³
2. 6.09 × 10²²
3. 6.022 × 10²³
4. 6.022 × 10²¹

Answer. 1. 6.68 × 10²³

Question 84. A change in the physical state can be brought about

1. Only when energy is given to the system
2. Only when energy is taken out from the system
3. when energy is either given to, or taken out from the system
4. without any energy change

Answer. 3. when energy is either given to, or taken out from the system