CBSE Class 9 Science Atoms and Molecules MCQs Set 01

Download CBSE MCQs for Class 9 Science: Chapter 03 Atoms and Molecules

Review structured MCQ sets for Class 9 Science Chapter 03 Atoms and Molecules. Built according to official CBSE guidelines, these downloadable questions support daily revision and core concept reinforcement.

Chapter-wise Objective Questions: Chapter 03 Atoms and Molecules

Access the complete set of multiple-choice questions for Chapter 03 Atoms and Molecules below. This focused format allows students to isolate specific topics for thorough review and uninterrupted practice alongside official CBSE textbooks.

Read the Atoms and Molecules Class 9 MCQ as per latest NCERT book

Question : 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
 
Answer : A
 
Question : Identify the correct symbol of gold:
(a) Go
(b) Ge
(c) Gd
(d) Au
 
Answer : D
 
Question : The combining capacity of an element is called
(a) Valency
(b) Atomicity
(c) Atomic number
(d) Valence electrons
 
Answer : A
 
Question : 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
 
Answer : C 
 
Question : 18g of water is electrolyse(d) The weight of oxygen obtained is:
(a) 16g
(b) 8g
(c) 4g
(d) 1g
 
Answer : A
 
Question : 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
 
Answer : D
 
Question : 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
 
Answer : A
 
Question : The formula of Calcium phosphate is:
(a) CaPO4
(b) Ca(PO4)2
(c) Ca3(PO4)2
(d) Ca2(PO4)3
 
Answer : C
 
Question : Molecular weight of CuSO4.5H2O is equal to:
(a) 249.5
(b) 159.5
(c) 159.5 X90
(d) 159.5 +10 + 16
 
Answer : A
 
Question : 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
 
Answer : D
 
Question : 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
 
Answer : B
 
Question : 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
 
Answer : D
 

Question. 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

Answer : A

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

Answer : C

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

Answer : A

Question. 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

Answer : D

Question. 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) I
(b) Iv< i
(c) I
(d) Iv

Answer : B

Question. 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

Answer : D

Question. 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

Answer : C

Question. 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 indivisible and indestructive ultimate particles
(c) Atoms combine in small whole number ratios to form compounds
(d) Atoms of different elements can have the same mass

Answer : D

Question. 16g of S8 contains:
(a) 6.023x1023 Atoms of S
(b) 6.023x1023/8 atoms of s
(c) 6.023x1023/2 atoms of S
(d) 6.023x1023/16 atoms of S

Answer : D

Question. 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

Answer : A

Question. 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

Answer : C

Question. 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

Answer : A

Question.
(a) Oxygen:
(b) diatomic
(c) Ozone :_______
i. Monoatomic
ii. Diatomic
iii. Triatomic
iv. Tetra atomic

Answer : C

Question.
(a) 24g of Mg: 1 mole
(b) 35.5g of Cl2: _________
i. 0.5mol
ii. 1 mol
iii. 2moles
iv. 2.5 moles

Answer : A

 
 
Question : 16g of S8 contains:
(a) 6.023x1023 Atoms of S
(b) 6.023x1023/8 atoms of s
(c) 6.023x1023/2 atoms of S
(d) 6.023x1023/16 atoms of S
 
Answer : D
 
Question : 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
 
Answer : A
 
Question : 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
 
Answer : C
 
 
Question :
(a) Oxygen: diatomic
(b) Ozone :_______
(a) Monoatomic
(b) Diatomic
(c) Triatomic
(d) Tetra atomic
 
Answer : C
 
Question :
(a) 24g of Mg: 1 mole
(b) 35.5g of Cl2: _________
(a) 0.5mol
(b) 1 mol
(c) 2moles
(d) 2.5 moles
 
Answer : A  

Question : 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

Answer : B

Question : 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

Answer : D

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

Answer : A

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

Answer : C

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

Answer : A

Question : 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

Answer : C

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

Answer : B

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

Answer : D

Question : 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

Answer : B

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

Answer : A

Question : 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

Answer : A

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

Answer : D

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

Answer : B

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

Answer : C

Question : 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

Answer : A

Question: 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

Answer: A

 

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