Class 9 Science Chapter 3 Atoms and Molecules MCQ Questions with Answer

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Atoms and Molecules Class 9 MCQ Questions with Answer

Class 9 Science MCQ with answers are given here to Chapter 3 Atoms and Molecules. These MCQs are based on the latest CBSE board syllabus and relate to the latest Class 9 Science syllabus. By Solving these Class 9 MCQs, you will be able to analyze all of the concepts quickly in the Chapter and get ready for the Class 9 Annual exam.

Learn Atoms and Molecules Class 9 MCQ with answers pdf free download according to the latest CBSE and NCERT syllabus. Students should prepare for the examination by solving CBSE Class 9 Atoms and Molecules MCQ with answers given below.

Question 1 : The combining capacity of an element is called

(a) Valency

(b) Atomicity

(c) Atomic number

(d) Valence electrons

Question 2 : Which is not represented by 1mole of Nitrogen gas?

(a) 6.023X10²³ molecules of N₂

(b) 12.046 X10²³ atoms of N₂

(c) 6.023X10²³ atoms of N₂

(d) 28g of N₂

Question 3 : If isotopic distribution of C-12 & C-14 is 98% and 2% respect(d)ely, then number of C-14 atoms in 12 g of C is:

(a) 1.244X10²²

(b) 1.244X10²³

(c) 3.88X10²²

(d) 3.88X10²²

Question 4 : Identify the correct symbol of gold:

(a) Go

(b) Ge

(c) Gd

(d) Au

Question 5 : The formula of Calcium phosphate is:

(a) CaPO₄

(b) Ca(PO₄)₂

(c) Ca₃(PO₄)₂

(d) Ca₂(PO₄)₃

Question 6 : Molecular weight of CuSO₄.5H₂O is equal to:

(a) 249.5

(b) 159.5

(c) 159.5 X90

(d) 159.5 +10 + 16

Question 7 : How many moles of electrons weigh 1 kg. Mass of an electron is 9.1X10^-31

(a) 6.022X10²³

(b) 6.022X10²³/9.1X10^-31

(c) 1X10³¹/9.1

(d) 10⁸/9.1X6.022

Question 8 : 18g of water is electrolyse(d) The weight of oxygen obtained is:

(a) 16g
(b) 8g
(c) 4g
(d) 1g

Question 9 : The balancing of chemical equations is in accordance with:

(a) Law of combining volumes

(b) Law of constant proportions

(c) Law of conservation of mass

(d) Both b and c

Question 10 : Which of the following is a correct statement:

(a) Na₂S is sodium sulphide, Na₂SO₃ is sodium sulphite, Na₂SO₄ is sodium sulphate

(b) Na₂S is sodium sulphite, Na₂SO₃ is sodium sulphide, Na₂SO₄ is sodium sulphate

(c) Na₂S is sodium sulphide, Na₂SO₃ is sodium sulphate, Na₂SO₄ is sodium sulphite

(d) Na₂S is sodium sulphite, Na₂SO₃ is sodium sulphite, Na₂SO₄ is sodium sulphide

Question 11 : 16g of S8 contains:

(a) 6.023×10²³ Atoms of S

(b) 6.023×10²³/8 atoms of s

(c) 6.023×10²³/2 atoms of S

(d) 6.023×10²³/16 atoms of S

Question 12 : Which of the following has the smallest number of molecules?

(a) 0.1 moles of CO₂

(b) 2g of H₂ at STP

(c) 16g of O₂ gas

(d) 3.4g of NH₃

Question 13 : Arrange the following in increasing number of molecules:

(a) 0.5moles of H₂

(b) 4g of H₂

(c) 18g of H₂O

(d). 2.2g of CO₂

(a) I <iii<(d)< ii

(b) Iv< i<iii<ii

(c) I<ii<iii<(d)

(d) Iv<iii<ii<i

Question 14 : Out of 1 g of oxygen gas, 1 g of oxygen atoms and 1g of ozone , maximum number of atoms are present in:

(a) 1g of oxygen gas

(b) 1g of oxygen atoms

(c) 1 g of ozone

(d) All have equal number of atoms

Question 15 : The number of atoms present in 0.5 moles of Nitrogen atoms is same as in:

(a) 12 g of C

(b) 24 g of Mg

(c) 8 g of O

(d) 32 g of S

Question 16 : Which of the following is not a postulate of Dalton’s atomic theory:

(a) All matter is made up of atoms

(b) Atoms are tiny ind(d)isible and indestruct(d)e ultimate particles

(c) Atoms combine in small whole number ratios to form compounds

(d) Atoms of different elements can have the same mass

Question 17 :

(a) 24g of Mg: 1 mole

(b) 35.5g of Cl₂: _________

(a) 0.5mol

(b) 1 mol

(c) 2moles

(d) 2.5 moles

Question 18 : An element X has valency equal to 3. What will be its formula with carbonate ions?

(a) X₂CO₃

(b) XCO₃

(c) X₂(CO₃)₃

(d) X(CO₃)₃

Question 19 : The mass of a single atom of an element X is 2.65X 10^-23g. The atomic mass and name of the element is:

(a) 16u, oxygen

(b) 16u, Sulphur

(c) 32u, oxygen

(d) 32u, Sulphur

Question 20 :

(a) Oxygen: diatomic

(b) Ozone :_______

(a) Monoatomic

(b) Diatomic

(c) Triatomic

(d) Tetra atomic

Question 21 : The word “mole” was introduced around 1896 by:           
(a) Wilhelm Ostwald
(b) John Dalton
(c) Avogadro
(d) Vergilious

Question 22 : One gram of which of the following contains largest number of oxygen atoms?    
(a) O
(b) O₂
(c) O₃
(d) All contains same

Question 23 : Percentage of calcium in calcium carbonate is          
(a) 40
(b) 30
(c) 48
(d) 36

Question 24 : A change in the physical state can be brought about    
(a) only when energy is g(d)en to the system
(b) only when energy is taken out from the system
(c) when energy is either g(d)en to, or taken out from the system
(d) without any energy change

Question 25 : An element X is tetravalent and another element Y is d(d)alent. The compound formed by these two elements will be:     
(a) XY
(b) XY₂
(c) X₂Y
(d) XY₄

Question 26 : Which of the following represents 12 u?         
(a) Mass of 1 hydrogen atom
(b) Mass of C-12 atom
(c) Mass of 0-16 atom
(d) 1/12th of mass of C-12 atom

Question 27 : The chemical symbol for sodium is          
(a) So
(b) Sd
(c) NA
(d) Na

Question 28 : Who laid the foundation of laws of Chemical Combination:        
(a) Democritus
(b) Lavoisier
(c) Dalton
(d) Proust

Question 29 : The molecule having an atomicity of 4 is:     
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

Question 30 : The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of:     
(a) Constant proportion
(b) Conservation of mass
(c) Multiple proportions
(d) Reciprocal proportions

Question 31 : Which of the following is not a postulate of Daltons atomic theory:
(a) Atoms of different elements can have the same mass
(b) All matter is made up of atoms
(c) Atoms are tiny indivisible and indestructive ultimate particles
(d) Atoms combine in small whole number ratios to form compounds

Question 32 : What is the formula mass unit of ZnO?          
(a) 18 u
(b) 81 u
(c) 88 u
(d) 188 u

Question 33 : Formula for Aluminium Oxide is:        
(a) AlO
(b) AlO₂
(c) Al₃O₂
(d) Al₂O₃

Question 34 : How many molecules are present in one gram of hydrogen?    
(a) 6.02 × 10²³
(b) 3.01 × 10²³
(c) 2.5 × 10²³
(d) 1.5 × 10²³

Question 35 : The correct symbol for silver is:           
(a) Ag
(b) S
(c) Ar
(d) AI

Question 36 : 1 u or 1 amu means                 
(a) 1/12th mass of C-12 atoms
(b) Mass of C-12 atom
(c) Mass of O-16 atom
(d) Mass of Hydrogen molecule

Question 37 : The number of atoms present in 0.5 moles of Nitrogen atoms is same as in:
(a) 12 g of C
(b) 8 g of O
(c) 24 g of Mg
(d) 32 g of S

Question 38 : Out of 1 g of oxygen gas, 1 g of oxygen atoms and 1g of ozone , maximum number of atoms are present in:
(a) All have equal number of atoms
(b) 1g of oxygen gas
(c) 1g of oxygen atoms
(d) 1 g of ozone

Question 39 : Arrange the following in increasing number of molecules:
i. 0.5moles of H₂ 
ii. 4g of H₂ 
iii. 18g of H₂O
iv. 2.2g of CO₂ 
(a) iv < i < iii < ii
(b) i < iii < iv < ii
(c) iv < iii < ii < i
(d) i < ii < iii < iv

Question 40 : a. 24g of Mg: 1 mole
              b. 35.5g of Cl₂: _________

(a) 0.5mol
(b) 1 mol
(c) 2moles
(d) 2.5 moles

Question 41 : a. Oxygen: diatomic
                  b. Ozone :_______

(a) Triatomic
(b) Monoatomic
(c) Diatomic
(d) Tetra atomic

Question 42: The mass of a single atom of an element X is 2.65X 10-²³g. The atomic mass and name of the element is:
(a) 16u, Sulphur
(b) 16u, oxygen
(c) 32u, oxygen
(d) 32u, Sulphur

Question 43 : An element X has valency equal to 3. What will be its formula with carbonate ions?
(a) X₂(CO₃)3
(b) X₂CO₃
(c) XCO₃
(d) X(CO₃)₃ 

Question 44 : Which of the following has the smallest number of molecules?
(a) 2g of H₂ at STP
(b) 3.4g of NH₃
(c) 0.1 moles of CO₂
(d) 16g of O₂ gas

Question 45 : 16g of S8 contains:
(a) 6.023×10²³/16 atoms of S
(b) 6.023×10²³ Atoms of S
(c) 6.023×10²³/8 atoms of s
(d) 6.023×10²³/2 atoms of S

Question 46 : 18g of water is electrolyse The weight of oxygen obtained is:
(a) 8g
(b) 16g
(c) 4g
(d) 1g

Question 47 : Which is not represented by 1mole of Nitrogen gas?
(a) 6.023X10²³ atoms of N₂
(b) 6.023X10²³ molecules of N₂
(c) 12.046 X10²³ atoms of N₂
(d) 28g of N₂ 

Question 48 : The combining capacity of an element is called
(a) Valency
(b) Atomicity
(c) Atomic number
(d) Valence electrons

Question 49 : How many moles of electrons weigh 1 kg. Mass of an electron is 9.1X10-³¹
(a) 10⁸/9.1X6.022
(b) 6.022X10²³
(c) 6.022X10²³/9.1X10-³¹
(d) 1X10³¹/9.1

Question 50 : Molecular weight of CuSO₄.5H₂O is equal to:
(a) 159.5 X90
(c) 249.5
(b) 159.5
(d) 159.5 +10 + 16

Question 51 : The formula of Calcium phosphate is:
(a) Ca₃(PO₄)₂
(b) CaPO₄
(c) Ca(PO₄)₂
(d) Ca2(PO₄)₃ 

Question 52: Which of the following is a correct statement:
(a) Na₂S is sodium sulphide, Na₂SO₃ is sodium sulphite, Na₂SO₄ is sodium sulphate
(b) Na₂S is sodium sulphite, Na₂SO₃ is sodium sulphide, Na₂SO₄ is sodium sulphate
(c)Na₂S is sodium sulphide, Na₂SO₃ is sodium sulphate, Na₂SO₄ is sodium sulphite
(d) Na₂S is sodium sulphite, Na₂SO₃ is sodium sulphite, Na₂SO₄ is sodium sulphide

Question 53 : The balancing of chemical equations is in accordance with:
(a) Both b and c
(b) Law of combining volumes
(c) Law of constant proportions
(d) Law of conservation of mass

Question 54 : The most remarkable concept that Dalton’s atomic theory proposed was that of the:
(a) atomic weight
(b) atomic mass
(c) molar mass
(d) none of the above

Question 55 : Who coined the term ‘Parmanu’ for the smallest indivisible particles?
(a) Leucippus
(b) L. Lavoisier
(c) Kanad
(d) None of them

Question 56 : Identify the correct symbol of Gold.
(a) Go
(b) Gd
(c) Ge
(d) Au

Question 57 : Identify the correct symbol of gold:
(a) Au
(b) Go
(c) Ge
(d) Gd

Question 58 : If isotopic distribution of C-12 & C-14 is 98% and 2% respectively, then number of C-14 atoms in 12 g of C is:
(a) 1.244X10²²
(b) 1.244X10²³
(c) 3.88X10²²
(d) 3.88X10²² 

Question 59 : Which of the following contains maximum number of molecules?
(a) 19 CO₂
(b) 1 g N₂
(c) 1 g H₂
(d) 1 g CH₄ 

Question 60 : The molecular formula of potassium nitrate is ________.
(a) KNO₃
(b) KNO
(c) KNO₂
(d) KON

Question 61 : What is the latin name of sodium?
(a) Kalium
(b) Plumbum
(c) Natrium
(d) None of the above

Question 62 : The combining capacity of an element is called
(a) Valency
(b) Atomicity
(c) Atomic number
(d) Valence electron

Question 63 : Which of the following statements is not true about an atom?
(a) Atoms are not able to exist independently.
(b) Atoms are the basic units from which molecules and ions are formed.
(c) Atoms are always neutral in nature.
(d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

Question 64 : The law of definite proportions was given by:
(a) John Dalton
(b) Humphry davy
(c) Proust
(d) Michael Faraday

Question 65 : The atomic mass of carbon is:
(a) 12
(b) 14
(c) 16
(d) 23

Question 66: Who coined the term ‘Parmanu’ for the smallest indivisible particles?
(a) Leucippus
(b) L. Lavoisier
(c) Kanad
(d) None of them

Question 67 : Which one of the following phrases would be incorrect to use?
(a) A mole of an element
(b) A mole of a compound
(c) An atom of an element
(d) An atom of a compound

Question 68 : The chemical symbol for barium is:
(a) B
(b) Ba
(c) Be
(d) Bi

Question 69 : The molecular formula of potassium nitrate is ________.
(a) KNO3
(b) KNO
(c) KNO2
(d) KO

Question 70 : The chemical symbol for nitrogen gas is
(a) Ni
(b) N2
(c) N+
(d) N

Question 71 : The molecule having an atomicity of 4 is:
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

Question 72 : How many times an atom of sulphur is heavier than an atom of carbon?
(a) 32 times
(b) 12 times
(c) 8/3 times
(d) 12/32 times

Question 73 . Which of the following represents a correct chemical formula?
(a) CaCl
(b) BiPO₄
(c) NaSO₄
(d) NaS

Question 74 : Which of the following statements is not true about an atom?
(a) Atoms are not able to exist independently.
(b) Atoms are the basic units from which molecules and ions are forme(d)
(c) Atoms are always neutral in nature.
(d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

Question 75 : Percentage of calcium in calcium carbonate is
(a) 40
(b) 30
(c) 48
(d) 36

Question 76 : The mass of sodium in 11.7 g of sodium chloride is:
(a) 2.3g
(b) 4.6g
(c) 6.9g
(d) 7.1g

Question 77 . Which of the following correctly represents 360g of water?
(i) 2 moles of water
(ii) 20 moles of water
(iii) 6.022 × 1023 molecules of water
(iv) 1.2044 × 1025 molecules of water
(a) (i)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)

Question 78 . The molecular formula of potassium nitrate is ________.
(a) KNO₃
(b) KNO
(c) KNO₂
(d) KON

Question 79 . Which of the following contains maximum number of molecules?
(a) 19 CO₂
(b) 1 g N₂
(c) 1 g H₂
(d) 1 g CH₄

Question 80 . 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The numbers of oxygen atoms in the solution are:
(a) 6.68 ×10²³
(b) 6.09 ×10²²
(c) 6.022 ×10²³
(d) 6.022 ×10²¹

Question 81 . What is the formula mass unit of ZnO?
(a) 18 u
(b) 81 u
(c) 88 u
(d) 188 u

Question 82 : The number of molecules in 16.0g of oxygen is:
(a) 6.02 × 10²³
(b) 6.02 ×10−²³
(c) 3.01 × 10−²³
(d) 3.01 × 10−²³

Question 83 : 4g of iodine and 14.2g of chlorine are made to react completely to yield a mixture of ICl and ICl3 . Calculate the ratio of moles of ICl and ICl3 :
(a) 1: 1
(b) 2: 1
(c) 3: 1
(d) 1: 2

Question 84 : One gram of which of the following contains largest number of oxygen atoms?
(a) O
(b) O2
(c) O3
(d) All contains same

Question 85 : The number of oxygen atoms in 4.4 g of CO₂ is approx.
(a) 6 × 10²²
(b) 6
(c) 12 × 10²³
(d) 1.2 × 10²³

Question 86 : The molecule having an atomicity of 4 is:
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

Question 87 : Choose the law of conservation of mass
(a) Mass neither be created nor formed
(b) Mass can neither be created nor reform
(c) Mass can neither be created nor destroyed
(d) Mass can neither be created nor alive

Question 88 : Which of the following represents the correct relation between Avogadro’s number (No), number of particles (N) and moles (n)?
(a) n = N / No
(b) n = No / N
(c) n = N No
(d) all are correct

Question 89 : When an atom loses electrons, it is called a (an) ______ and has a _____ charge.
(a) Anion, positive
(b) Cation, positive
(c) Anion, negative
(d) Cation, negative

Question 90: Selenium ingested in the amount of 90 micrograms per day causes loss of hair. How many selenium atoms are in this size sample? (Atomic weight: Se = 78.96.)
(a) 6.9 × 1023
(b) 8.8 × 1017
(c) 8.8 × 1022
(d) 6.9 × 1017

Question 91 : …………….. for some elements as proposed by Dalton.
(a) Shape
(b) Initiator
(c) Symbol
(d) Color

Question 92 : The law of definite proportions was given by:
(a) John Dalton
(b) Humphry davy
(c) Proust
(d) Michael Faraday

Question 93 : Atomic radius is measured in…………
(a) Kg
(b) cm
(c) Mm
(d) nm

Question 94: The chemical symbol for barium is:
(a) B
(b) Ba
(c) Be
(d) Bi

Question 95 :

a. Oxygen: diatomic

b. Ozone :_______

• a) Tetra atomic
• b) Monoatomic
• c) Diatomic
• d) Triatomic 

Question 96: The mass of a single atom of an element X is 2.65X 10^-23g. The atomic mass and name of the element is:

• a) 16u, oxygen
• b) 16u, Sulphur
• c) 32u, oxygen
• d) 32u, Sulphur

Question 97: The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of:
(a) Constant proportion
(b) Conservation of mass
(c) Multiple proportions
(d) Reciprocal proportions

Question 98: The number of atom in 4.25g of NH3 is approximately:
(a) 1×10²³
(b) 2×10²³
(c) 4×10²³
(d) 6×10²³

Question 99: How many molecules are present in one gram of hydrogen?
(a) 6.02×10²³
(b) 3.01×10²³
(c) 2.5×10²³
(d) 1.5×10²³

Question 100: Which of the following is not a postulate of Daltons atomic theory:

• a) Atoms of different elements can have the same mass
• b) All matter is made up of atoms
• c) Atoms are tiny indivisible and indestructive ultimate particles
• d) Atoms combine in small whole number ratios to form compounds

Question 101: 

a. 24g of Mg: 1 mole

b. 35.5g of Cl₂: _________

• a) 0.5mol
• b) 1 mol
• c) 2moles
• d) 2.5 moles

Question 102 : Molecular weight of CuSO₄.5H₂O is equal to:

• a) 249.5
• b) 159.5
• c) 159.5 X90
• d) 159.5 +10 + 16

Question 103: An element X has valency equal to 3. What will be its formula with carbonate ions?

• a) X₂(CO₃)₃
• b) X₂CO₃
• c) XCO₃
• d) X(CO₃)₃

Question 103: Which of the following has the smallest number of molecules?

• a) 2g of H₂ at STP
• b) 3.4g of NH₃
• c) 0.1 moles of CO₂ 
• d) 16g of O₂ gas

Question 104: 16g of S8 contains:

• a) 6.023×10²³/8 atoms of s
• b) 6.023×10²³ Atoms of S
• c) 6.023×10²³/16 atoms of S 
• d) 6.023×10²³/2 atoms of S

Question 105: The number of atoms present in 0.5 moles of Nitrogen atoms is same as in:

• a) 8 g of O
• b) 12 g of C
• c) 24 g of Mg
• d) 32 g of S

Question 106: Out of 1 g of oxygen gas, 1 g of oxygen atoms and 1g of ozone , maximum number of atoms are present in:

• a) 1g of oxygen atoms
• b) 1g of oxygen gas
• c) All have equal number of atoms 
• d) 1 g of ozone

Question 107: Arrange the following in increasing number of molecules:

i. 0.5moles of H₂

ii. 4g of H₂

iii. 18g of H₂O

iv. 2.2g of CO₂

• a) iv < i < iii < ii
• b) i < iii < iv < ii
• c) iv < iii < ii < i
• d) i < ii < iii < iv

Question 108: How many moles of electrons weigh 1 kg. Mass of an electron is 9.1X10^-31

• a) 10⁸/9.1X6.022
• b) 6.022X10²³
• c) 6.022X10²³/9.1X10^-31
• d) 1X10³¹/9.1

Question 109: Identify the correct symbol of gold:

• a) Au
• b) Go
• c) Ge
• d) Gd

Question 110: If isotopic distribution of C-12 & C-14 is 98% and 2% respectively, then number of C-14 atoms in 12 g of C is:

• a) 1.244X10²²
• b) 1.244X10²³
• c) 3.88X10²²
• d) 3.88X10²²

Question 111: The formula of Calcium phosphate is:

• a) Ca₃(PO₄)₂
• b) CaPO₄
• c) Ca(PO₄)₂
• d) Ca₂(PO₄)₃

Question 112: Which of the following is a correct statement:

• a) Na₂S is sodium sulphide, Na₂SO₃ is sodium sulphite, Na₂SO₄ is sodium sulphate
• b) Na₂S is sodium sulphite, Na₂SO₃ is sodium sulphide, Na₂SO₄ is sodium sulphate
• c) Na₂S is sodium sulphide, Na₂SO₃ is sodium sulphate, Na₂SO₄ is sodium sulphite
• d) Na₂S is sodium sulphite, Na₂SO₃ is sodium sulphite, Na₂SO₄ is sodium sulphide

Question 113: The balancing of chemical equations is in accordance with:

• a) Both b and c
• b) Law of combining volumes
• c) Law of constant proportions
• d) Law of conservation of mass

Question 114: 18g of water is electrolyse The weight of oxygen obtained is:

• a) 16g
• b) 8g
• c) 4g
• d) 1g

Question 115: Which is not represented by 1mole of Nitrogen gas?

• a) 6.023X10²³ atoms of N₂
• b) 6.023X10²³ molecules of N₂
• c) 12.046 X10²³ atoms of N₂
• d) 28g of N₂

Question 116: The combining capacity of an element is called

• a) Valency
• b) Atomicity
• c) Atomic number
• d) Valence electrons

Question 117 . The law of definite proportions was given by:         
(a) John Dalton
(b) Humphry davy
(c) Proust
(d) Michael Faraday

Question 118. The most remarkable concept that Dalton’s atomic theory proposed was that of the:    
(a) atomic weight
(b) atomic mass
(c) molar mass
(d) none of the above

Question 119. Who coined the term ‘Parmanu’ for the smallest indivisible particles?          
(a) Leucippus
(b) L. Lavoisier
(c) Kanad
(d) None of them

Question 120. Which of the following contains maximum number of molecules?            
(a) 19 CO₂ 
(b) 1 g N₂ 
(c) 1 g H₂ 
(d) 1 g CH₄

Question 121. The molecular formula of potassium nitrate is ________.         
(a) KNO₃
(b) KNO
(c) KNO₂
(d) KON

Question 122. What is the latin name of sodium?       
(a) Kalium
(b) Plumbum
(c) Natrium
(d) None of the above

Question 123. The combining capacity of an element is called      
(a) Valency
(b) Atomicity
(c) Atomic number
(d) Valence electron

Question 124. Which of the following statements is not true about an atom?           
(a) Atoms are not able to exist independently.
(b) Atoms are the basic units from which molecules and ions are formed.
(c) Atoms are always neutral in nature.
(d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

Question 125. Who coined the term ‘Parmanu’ for the smallest indivisible particles?      
(a) Leucippus
(b) L. Lavoisier
(c) Kanad
(d) None of them

Question 126. The mass of sodium in 11.7 g of sodium chloride is:     
(a) 2.3g
(b) 4.6g
(c) 6.9g
(d) 7.1g

Question 127. Which of the following correctly represents 360g of water?
(i) 2 moles of water
(ii) 20 moles of water
(iii) 6.022 × 1023 molecules of water
(iv) 1.2044 × 1025 molecules of water
(a) (i)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)

Question 128. The molecular formula of potassium nitrate is ________.
(a) KNO₃
(b) KNO
(c) KNO₂
(d) KON

Question 129. Identify the correct symbol of Gold.     
(a) Go
(b) Gd
(c) Ge
(d) Au

Whoever needs to take the CBSE Class 9 Board Exam should look at this MCQ. To the Students who will show up in CBSE Class 9 Science Board Exams, It is suggested to practice more and more questions. Aside from the sample paper you more likely had solved. These Atoms and Molecules Class 9 MCQ are ready by the subject specialists themselves.

Question 130. Which one of the following phrases would be incorrect to use?      
(a) A mole of an element
(b) A mole of a compound
(c) An atom of an element
(d) An atom of a compound

Question 131. The chemical symbol for barium is:       
(a) B
(b) Ba
(c) Be
(d) Bi

Question 132. The molecular formula of potassium nitrate is ________.      
(a) KNO₃
(b) KNO
(c) KNO₂
(d) KO

Question 133. The atomic mass of carbon is:       
(a) 12
(b) 14
(c) 16
(d) 23

Question 134. Which of the following represents a correct chemical formula?
(a) CaCl
(b) BiPO₄
(c) NaSO₄
(d) NaS

Question 135. Which of the following statements is not true about an atom?
(a) Atoms are not able to exist independently.
(b) Atoms are the basic units from which molecules and ions are forme(d)
(c) Atoms are always neutral in nature.
(d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

Question 136. Percentage of calcium in calcium carbonate is
(a) 40
(b) 30
(c) 48
(d) 36

Question 137. The number of oxygen atoms in 4.4 g of CO₂ is approx.
(a) 6 × 10²²
(b) 6
(c) 12 × 10²³
(d) 1.2 × 10²³

Question 138. Which of the following contains maximum number of molecules?
(a) 19 CO₂
(b) 1 g N₂
(c) 1 g H₂
(d) 1 g CH₄

Question 139 . 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The numbers of oxygen atoms in the solution are:
(a) 6.68 ×10²³
(b) 6.09 ×10²²
(c) 6.022 ×10²³
(d) 6.022 ×10²¹

Question 140. What is the formula mass unit of ZnO?
(a) 18 u
(b) 81 u
(c) 88 u
(d) 188 u

Question 141. The chemical symbol for nitrogen gas is
(a) Ni
(b) N2
(c) N+
(d) N

Question 142. The molecule having an atomicity of 4 is:
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

Question 143. How many times an atom of sulphur is heavier than an atom of carbon?
(a) 32 times
(b) 12 times
(c) 8/3 times
(d) 12/32 times

Question 144. Atomic radius is measured in…………
(a) Kg
(b) cm
(c) Mm
(d) nm

Question 145. The chemical symbol for barium is:
(a) B
(b) Ba
(c) Be
(d) Bi

Question 146 . Which of the following represents the correct relation between Avogadro’s number (No), number of particles (N) and moles (n)?
(a) n = N / No
(b) n = No / N
(c) n = N No
(d) all are correct

Question 147. When an atom loses electrons, it is called a (an) ______ and has a _____ charge.
(a) Anion, positive
(b) Cation, positive
(c) Anion, negative
(d) Cation, negative

Question 148. The molecule having an atomicity of 4 is:
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

Question 149 . Choose the law of conservation of mass
(a) Mass neither be created nor formed
(b) Mass can neither be created nor reform
(c) Mass can neither be created nor destroyed
(d) Mass can neither be created nor alive

Question 150. Selenium ingested in the amount of 90 micrograms per day causes loss of hair. How many selenium atoms are in this size sample? (Atomic weight: Se = 78.96.)
(a)  6.9 × 10²³
(b) 8.8 × 10¹⁷
(c) 8.8 × 10²²
(d) 6.9 × 10¹⁷

Question 151. …………….. for some elements as proposed by Dalton.
(a) Shape
(b) Initiator
(c) Symbol
(d) Color

Question 152. The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of:
(a) Constant proportion
(b) Conservation of mass
(c) Multiple proportions
(d) Reciprocal proportions

Question 153. The number of atom in 4.25g of NH3 is approximately:
(a)  1×10²³
(b) 2×10²³
(c) 4×10²³
(d) 6×10²³

Question 154. How many molecules are present in one gram of hydrogen?
(a) 6.02×10²³
(b) 3.01×10²³
(c) 2.5×10²³
(d) 1.5×10²³

Question 155. The number of molecules in 16.0g of oxygen is:
(a)  6.02 × 10²³
(b) 6.02 ×10⁻²³
(c) 3.01 × 10⁻²³
(d) 3.01 × 10²³

Question 156.4g of iodine and 14.2g of chlorine are made to react completely to yield a mixture of ICl and ICl3 . Calculate the ratio of moles of ICl and ICl3 :
(a) 1: 1
(b) 2: 1
(c) 3: 1
(d) 1: 2

Question 157. One gram of which of the following contains largest number of oxygen atoms?
(a) O
(b) O2
(c) O3
(d) All contains same

Question 158. The law of definite proportions was given by:
(a) John Dalton
(b) Humphry davy
(c) Proust
(d) Michael Faraday

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