Here we are providing Class 9 Science Objective Chapter – 3 Atoms and Molecules because its very important for Class 9 students as we all know that every board exam question has MCQs so that students should practice these questions so that students can get good marks in board. Class 9 Science Objective Chapter – 3 Atoms and Molecules is an extremely important and its also a year in which students learn the fundamentals of concepts that help them lay a solid foundation for their higher education. Here we are providing in Class Class 9 Science Objective Chapter – 3 Atoms and Molecules 100+ questions so that students practice more and more. If you want class wise Notes Then Click Here
Class 9 Science Objective Chapter – 3 Atoms and Molecules
1.The chemical symbol for nitrogen gas is
( A ) Ni
( B ) N2
( C ) N+
( D ) N
Ans – ( B )
2. The number of atoms present in one molecule of an element is called as:
( A ) Empirical formula
( B ) Molecule
( C ) Atomicity
( D ) Compound
Ans – ( C )
3.The chemical symbol for sodium is:
( A ) So
( B ) Sd
( C ) NA
( D ) Na
Ans – ( D )
4. Calculate the formula unit mass of ZnCl2?
( A ) 137 u
( B ) 124 u
( C ) 123 u
( D ) 111 u
Ans – ( A )
5. 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)
Ans – ( D )
6. Which of the following pair of elements represents a mole ratio of 1:1?
( A ) 20 g of sodium and 20 g of calcium
( B ) 7 g of nitrogen and 12 gm of sodium
( C ) 10 g of calcium and 6 g of carbon
( D ) 14 g of nitrogen and 24 g of magnesium
Ans – ( D )
7.The chemical symbol for sodium is
( A ) So
( B ) Sd
( C ) NA
( D ) Na
Ans – ( D )
8. Which of the following is the correct IUPAC symbol for the element Cobalt?
( A ) Co
( B ) Cb
( C ) C
( D ) none of these
Ans – ( A )
9. 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.
Ans – ( D )
10. Which of the following can be used to see atoms?
( A ) Scanning tunneling microscope
( B ) Microscope
( C ) Most powerful microscope
( D ) Optical microscope
Ans – ( A )
11.Which of the following would weigh the highest?
( A ) 0.2 mole of sucrose (C12H22O11)
( B ) 2 moles of CO2
( C ) 2 moles of CaCO3
( D ) 10 moles of H2O
Ans – (C )
12. NaCl molecule is made of which of the following ions?
( A ) Na cation and Cl anion
( B ) Cl cation and Na anion
( C ) Both Na and Cl cation
( D ) Both Na and Cl anion
Ans – ( A )
13.Which of the following has maximum number of atoms?
( A ) 18 g of H2O
( B ) 18 g of O2
( C ) 18 g of CO2
( D ) 18 g of CO4
Ans – ( D )
14. 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
Ans – ( A )
15.Which of the following correctly represents 360 g of water?
(i) 2 moles of H2O
(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)
Ans – ( D )
16. If 12 grams of carbon has n atoms, then the number of atoms in 12 grams of magnesium will be:
( A ) 2n
( B ) 3n
( C ) n/2
( D ) n
Ans – ( C )
17. Which of the following contains maximum number of molecules?
( A ) 19 CO2
( B ) 1 g N2
( C ) 1 g H2
( D ) 1 g CH4
Ans – ( C )
18. 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are
( A ) 6.68 × 1023
( B ) 6.09 × 1022
( C ) 6.022 × 1023
( D ) 6.022 × 102321
Ans – ( A )
19. Which of the following is correct pair of elements and its symbol?
( A ) Silver – Si
( B ) Sodium – So
( C ) Potassium – Pt
( D ) Sulphur – S
Ans – ( D )
20. A sample of NH3 molecule irrespective of source contains 82.35% Nitrogen and 17.65% of Hydrogen by mass. This data supports:
( A ) Law of Conservation of Mass
( B ) Las of Multiple Proportions
( C ) Law of Definite Proportions
( D ) Avogadro’s Law
Ans – ( C )
21.A change in the physical state can be brought about
( A ) only when energy is given to the system
( B ) only when energy is taken out from the system
( C ) when energy is either given to, or taken out from the system
( D ) without any energy change
Ans – ( C )
22. How many moles are present in 40 g of He?
( A ) 10 moles
( B ) 11 moles
( C ) 13 moles
( D ) 12 moles
Ans – ( A )
23.Who coined the term ‘Parmanu’ for the smallest indivisible particles?
( A ) Leucippus
( B ) L. Lavoisier
( C ) Kanad
( D ) None of them
Ans – ( C )
24.The relative molecular mass of Na2S2O3.5H2O is
( A ) 250 amu
( B ) 250 g
( C ) 248 amu
( D ) 248 g
Ans – ( C )
25.The radius of a hydrogen atom is:
( A ) 10-2
( B ) 10-4
( C ) 10-9
( D ) 10-10
Ans – ( D )
26.Which of the following has maximum number of atom?
( A ) 18 g H2O
( B ) 18 g of O2
( C ) 18 g of CO2
( D ) 18 g of CH4
Ans – ( D )
27.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 them
Ans – ( B )
28.Percentage of calcium in calcium carbonate is
( A ) 40
( B ) 30
( C ) 48
( D ) 36
Ans – ( A )
29.The atomic mass of carbon is:
( A ) 12
( B ) 14
( C ) 16
( D ) 23
Ans – ( A )
30.Which has maximum number of molecules?
( A ) 1 g of CO2
( B ) 1 g of N2
( C ) 1 g of H2
(d 1 g of CH4
Ans – ( C )
31.What mass of carbon dioxide (CO2) will contain 3.011 × 1023 molecules?
( A ) 11.0 g
( B ) 22.0 g
( C ) 4.4 g
( D ) 44.0 g
Ans – ( B )
32.Compounds composed of metals and non-metals contain:
( A ) non-charged species
( B ) charged species
( C ) both of them
( D ) none of them
Ans – ( B )
33. Identify the symbol used to represent Avogadro’s number.
( A ) MA
( B ) AO
( C ) AN
( D ) NA
Ans – ( D )
34.The value of Avogadro’s constant is:
( A ) 6.0 × 1024
( B ) 6.01 × 1022
( C ) 6.022 × 1023
( D ) 6.022 × 10-23
Ans – ( C )
35. Law of conservation of mass can be derived from which postulate of Dalton’s atomic theory?
( A ) Atoms of a given element have same mass and chemical properties.
( B ) Matter is made of tiny particles.
( C ) Atom can neither be created nor destroyed.
( D ) The relative number and kind of atoms are constant in a given compound.
Ans – ( C )
36.The formula of ammonium sulphate is:
( A ) NHSO4
( B ) NH4SO2
( C ) NHSO3
( D ) (NH4)2SO4
Ans – ( D )
37. Valency of hydrogen is 1 and that of sulphur is 2. What should be the formula of hydrogen sulphide?
( A ) HS
( B ) H2S2
( C ) HS2
( D ) H2S
Ans – ( D )
38.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
Ans – ( C )
39.The word “mole” was introduced around 1896 by:
( A ) Wilhelm Ostwald
( B ) John Dalton
( C ) Avogadro
( D ) Vergilious
Ans – ( A )
40. Calculate the number of Mg atoms in 0.024 g of Mg
( A ) 6.022 × 1021 Mg atoms
( B ) 6.22 × 1023 Mg atoms
( C ) 6.022 × 1020 Mg atoms
( D ) 6.022 × 1025 Mg atoms
Ans – ( C )
41.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
Ans – ( D )
42. One atomic mass unit is a mass unit equal to exactly one twelfth (1/12th) the mass of one atom of ___________.
( A ) Carbon-12
( B ) Nitrogen -14
( C ) Carbon-1
( D ) Silicon-14
Ans – ( A )
43.The chemical symbol for sodium is:
( A ) So
( B ) Sd
( C ) NA
( D ) Na
Ans – ( D )
44. If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?
( A ) The reactants must contain more complex molecules than the products do.
( B ) The products must have different physical state than the reactants.
( C ) The total mass of the reactants must equal the total mass of the products.
( D ) The density of the reactants must equal the density of the products.
Ans – ( C )
45.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.
Ans – ( D )
46. 9 grams of water decompose to give:
( A ) 4g oxygen and 16g hydrogen
( B ) 2g hydrogen and 1g oxygen
( C ) 8g oxygen and 1g hydrogen
( D ) none
Ans – ( C )
47.Which of the following has a maximum number of atoms?
( A ) 18 g of H2O
( B ) 18 g of O2
( C ) 18 g of CO2
( D ) 18 g of CH4
Ans – ( D )
48. Who gave the Law of constant proportions?
( A ) Cavendish
( B ) Proust
( C ) Dalton
( D ) Lavoisier
Ans – ( B )
49.Which of the following would weigh the highest?
( A ) 0.2 mole of sucrose (C12H22O11)
( B ) 2 moles of CO2
( C ) 2 moles of CaCO3
( D ) 10 moles of H2O
Ans – ( C )
50. According to Law of conservation of mass, mass of reactants wil be equal to the mass of:
( A ) Catalysts
( B ) Products
( C ) Apparatus used for reaction
( D ) Gases evolved
Ans – ( B )
51. 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
Ans – ( C )
52. How do atoms usually exist in nature?
( A ) In the form of molecules
( B ) In the form of ions
( C ) In the free state
( D ) In the form of molecules and Ions
Ans – ( D )
53.The molecule having an atomicity of 4 is:
( A ) Sulphate molecule
( B ) Ozone molecule
( C ) Phosphorus molecule
( D ) Methane molecule
Ans – ( C )
54. What is the mass of 0.5 mole of Hydrogen atom
( A ) 2.0 g
( B ) 1.5 g
( C ) 1 g
( D ) 0.5 g
Ans – ( D )
55. Energy can neither be created nor destroyed. it is a………………
( A ) Energy recreation
( B ) Energy is cannot reform
( C ) Law of conservation of energy
( D ) Law of conservation
Ans – ( C )
