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Chemistry Class 9 Chapter 2


Updated: 03 Sep 2023

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Chemistry Class 9 Chapter 2 is about the “Structure of an Atom.” This article includes topics such as Rutherford’s Atomic Model, Neil Bohr’s Atomic Theory, Fundamental Particles of an atom like Electrons, Protons and Neutron, Electronic Configuration and Isotopes.

Chemistry Class 9 Chapter 2 Notes

Chemistry 9th Class Chapter 2

Structure of an Atom

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Chemistry Class 9 Chapter 2

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Chemistry Class 9 Chapter 2-MCQs

Dalton Atomic Theory

1. A Greek philosopher “Democritus” suggested that all———— can be further divided into tiny particles.
(a) matter
(b) substances
(c) elements
(d) All of them
Show Answer

All of them


2. The name of atom was given from the Greek word ————- which means indivisible.
(a) atomos
(b) atomics
(c) Halogens
(d) None of these
Show Answer

atoms


3. The word atom was first used —————.
(a) 400AD
(b) 400 BC
(c) 600AD
(d) 600BC
Show Answer

400 BC


4. No further work on atom was done until the ————– century.
(a) 18th
(b) 20th
(c) 19th
(d) 21st
Show Answer

19th


5. John Dalton, after a lot of experiments, concluded that all matter must be composed of tiny particles called —-.
(a) Atom
(b) Element
(c) isotope
(d) None of these
Show Answer

Atom


6. John Dalton states that an atom is ——————-.
(a) Invincible
(b) Indivisible
(c) Invisible
(d) None of these
Show Answer

Indivisible


7. John Dalton presented his own theory about atom in —————–.
(a) 1806
(b) 1906
(c) 1808
(d) 1908
Show Answer

1808


8. ————–is composed of very small particles called atoms.
(a) Matter
(b) Energy
(c) Numbers
(d) All of these
Show Answer

Matter


9. Atom can neither be created nor ———————.
(a) Formulated
(b) Destroyed
(c) combined
(d) None of these
Show Answer

Destroyed


10. Atoms combine with each other in ————– number ratio.
(a) Integers
(b) Quadratic
(c) Whole
(d) None of these
Show Answer

Whole


11. Atoms of particular element are ———— in size shape, mass and also in other properties.
(a) Different
(b) Identical
(c) Atomic
(d) None of these
Show Answer

Identical


12. All chemical reactions occur due to the combination or ————— of atoms.
(a) Separation
(b) Distillation
(c) Filtration
(d) None
Show Answer

Separation


Rutherford’s Atomic Model

Rutherford’s Experiment

Main Points of Rutherford’s Atomic Model

Drawbacks of Rutherford’s Atomic Model

13. In———-, Rutherford performed an experiment to know the arrangement of electron and protons in an atom.
(a) 1910
(b) 1912
(c) 1911
(d) 1913
Show Answer

1911


14. In Rutherford experiment which part of the atom has been discovered?
(a) Energy levels
(b) Nucleus
(c) Other
(d) None
Show Answer

Nucleus


15. ————— performed an experiment to determine the internal structure of the atom in 1911.
(a) J.J Thompson
(b) Max plank
(c) Rutherford
(d) None of these
Show Answer

Rutherford


16. In Rutherford experiment, what he has used?
(a) Gold foil
(b) Gold bar
(c) Silver foil
(d) Tin plates
Show Answer

Gold foil


17. He bombarded the ________ particles on gold foil from a radioactive source.
(a) Beta
(b) Alpha
(c) Gamma
(d) None of these
Show Answer

Alpha


18. What radioactive source does Rutherford used?
(a) Polonium
(b) Thorium
(c) Radon
(d) None of these
Show Answer

Polonium


19. This experiment showed that most of the volume occupied by the atom is —————.
(a) Bulky
(b) Small
(c) Empty
(d) None of these
Show Answer

Empty


20. From this experiment, Rutherford concluded that an atom contains a ———– portion i.e. nucleus.
(a) Negative
(b) Positive
(c) Neutral
(d) None of these
Show Answer

Positive


21. Similar charges ————–each other.
(a) Repel
(b) Attract
(c) Articulate
(d) All of these
Show Answer

Repel


22. On the basis of his conclusion drawn from the experiment, Rutherford proposed a new model at atom called ————-model.
(a) Planetary
(b) Universal
(c) Room & Cat
(d) None of these
Show Answer

Planetary


23. Atom consists of positively charged nucleus which contains ———and neutrons.
(a) Electrons
(b) Protons
(c) Fundamental particles
(d) None of these
Show Answer

Protons


24. Electrons are ————around the nucleus just like the planets around the sun.
(a) Stand still
(b) Gathered
(c) Revolving
(d) None of these
Show Answer

Revolving


25. The electrons around the nucleus would require ————- force.
(a) Centripetal
(b) Centrifugal
(c) Net
(d) Average
Show Answer

Centripetal


26. The size of the ————- is very small as compared to the size of atom.
(a) proton
(b) Neutron
(c) Nucleus
(d) All of them
Show Answer

All of them


27. Atom is ———— because electrons and protons will cancel the effect of each other.
(a) Negatively charge
(b) Neutral
(c) Positively charged
(d) None of these
Show Answer

Neutral


28. Rutherford atomic model of an atom resembles our ________ system.
(a) Solar
(b) Universal
(c) Gravitational
(d) None of these
Show Answer

Solar


29. Rutherford model is applicable to neutral bodies and not on ————.
(a) Isotopes
(b) Energy
(c) Charged bodies
(d) None of these
Show Answer

Charged bodies


30. According to which scientist, electrons are charged bodies revolving around the nucleus and emit energy.
(a) Rutherford
(b) Schrodinger
(c) Maxwell
(d) None of these
Show Answer

Maxwell


31. If electrons radiate energy continuously then the ———–spectrum will be obtained.
(a) Line
(b) Continuous
(c) Both
(d) None of these
Show Answer

Continuous


32. Rutherford atomic model does not provide any explanation about ———— properties of elements.
(a) Chemical
(b) Physical
(c) Elemental
(d) None of these
Show Answer

Chemical


Neil Bohr’s Atomic Theory

33. In ————-, Neil Bohr proposed a new atomic theory to overcome the defects of Rutherford atomic model.
(a) 1901
(b) 1910
(c) 1915
(d) 1913
Show Answer

1913


34. Bohr considered ———-atom as a model.
(a) Helium
(b) Hydrogen
(c) Thorium
(d) None of these
Show Answer

Hydrogen


35. Electrons are revolving around the fixed circular path called ————-.
(a) Shells
(b) Orbits
(c) cycles
(d) Both a and b
Show Answer

Both a and b


36. Each shell has a —————– energy.
(a) Fixed
(b) variable
(c) No
(d) None of these
Show Answer

Fixed


37. The farther the electron from the nucleus, the ———— will be the energy and vice versa.
(a) Lower
(b) Higher
(c) Intermediate
(d) None of these
Show Answer

Higher


38. The ________ of an object is fixed.
(a) Frequency
(b) Volume
(c) Energy
(d) None of these
Show Answer

Energy


39. ∆E=E_2-E_1=h \mu In ths equation what is “h”?
(a) Plank’s constant
(b) Max constant
(c) Variable
(d) None of these
Show Answer

Plank’s constant


40 Electrons can’t stay in ———shells.
(a) 1st
(b) 2nd
(c) Between
(d) None of these
Show Answer

Between


To Download Complete Notes of Class 9 Chemistry Notes, Click the link.

Fundamental Particles of an atom

Electron

Proton

Neutron

41. Modern research show that an atom consist of ————— subatomic particles.
(a) 13
(b) 03
(c) 05
(d) None of these
Show Answer

03


42. Election is ————— charged particle.
(a) Negatively
(b) Positively
(c) Neutral
(d) All of these
Show Answer

Negatively


43. Mass of electron is ————–.
(a) 9.11 \times 10^{31} kg
(b) 9.11 \times 10^{-31} kg
(c) 6.023 \times 10^{23} kg
(d) All of these
Show Answer

9.11 \times 10^{-31} kg


44. Proton is a ———— charged particle.
(a) Negatively
(b) Positively
(c) Neutral
(d) None of these
Show Answer

Positively


45. Mass of proton is —————.
(a) 1.6726 \times 10^{-27} \ kg
(b) 9.11 \times 10^{-31} \ kg
(c) 1.37 \times 10^6 \ kg
(d) All of these
Show Answer

1.6726 \times 10^{-27} \ kg


46. Proton is ———– times heavier than electron.
(a) 1847
(b) 1827
(c) 1837
(d) All of these
Show Answer

1837


47. Neutron is a ————- particle because it has no charge.
(a) Negative
(b) Positive
(c) Neutral
(d) None of these
Show Answer

Neutral


48. Neutron is ———– times Havier than proton.
(a) 05
(b) 15
(c) 50
(d) 150
Show Answer

05


Electronic Configuration

Energy Level

s and p Sub-Shell

Shell (Orbit)

Sub-Shell

49. The ———— of electrons around the nucleus in shells is called electronic configuration.
(a) Separation
(b) Distribution
(c) Catenation
(d) None of these
Show Answer

Distribution


50. These shells are represented by ————.
(a) Alphabets
(b) Numeric
(c) Romans
(d) None of these
Show Answer

Alphabets


51. The maximum number of electrons in a particular shell is given by the formula ————.
(a) 4n^2
(b) 2n^3
(c) 4n^3
(d) 2n^2
Show Answer

2n^2


52. How many electrons are there K-shell?
(a) 2
(b) 8
(c) 18
(d) 32
Show Answer

2


53. How many electrons are there in L-shell?
(a) 2
(b) 8
(c) 18
(d) 32
Show Answer

8


54. How many electrons are there in M-shell?
(a) 2
(b) 8
(c) 18
(d) 32
Show Answer

18


55. How many electrons are there in N-shell?
(a) 2
(b) 8
(c) 18
(d) 32
Show Answer

32


56. A shell or orbit is also is also called ———–.
(a) Energy level
(b) Hertz
(c) Atomic mass
(d) None of these
Show Answer

Energy level


57. How many sub-shall are there in a shell?
(a) 14
(b) 10
(c) 04
(d) None of these
Show Answer

04


58. Which of them are sub-shell?
(a) s, p, d, f
(b) x, y, z
(c) K, L, M, N
(d) None of these
Show Answer

s, p, d, f


59. “s” sub –shell stands for ————-.
(a) Specific
(b) Sharp
(c) Sonic
(d) All of these
Show Answer

Sharp


60 “p” sub-shell stands for —————
(a) Principal
(b) principle
(c) Para-magnetic
(d) None of these
Show Answer

Principal


61 “d” sub –shell stands for ————-.
(a) Drainage
(b) dissolved
(c) diffused
(d) All of these
Show Answer

diffused


62. “f” sub-shell stand for———–.
(a) Fermium
(b) fundamental
(c) Fencing
(d) None of these
Show Answer

fundamental


63. “f” sub-shell can accommodate————- electrons.
(a) 2
(b) 6
(c) 10
(d) 14
Show Answer

14


64. Complete the electronic configuration of carbon atom i.e. 1s^2, 2S^2, ————-.
(a) 2p^2
(b) 2p^3
(c) 2p^4
(d) 2p^5
Show Answer

2p^2


Isotopes

65. Atoms of the same element having same atomic number but different ———– is called isotopes.
(a) Density
(b) Mobility
(c) Mass number
(d) None of these
Show Answer

Mass number


66. Atoms having same number of protons and electrons but differ number of neutrons are called ———–.
(a) Metallurgy
(b) Isotopes
(c) Surface area
(d) None of these
Show Answer

Isotopes


Isotopes of Hydrogen

67. How many isotopes hydrogen has?
(a) 03
(b) 06
(c) 09
(d) 12
Show Answer

03


68. Protium, deuterium and tritium are the isotopes of ————-.
(a) carbon
(b) chlorine
(c) Hydrogen
(d) None of these
Show Answer

Hydrogen


69. What is the most abundant isotope of hydrogen?
(a) Protium
(b) Deuterium
(c) tritium
(d) None of these
Show Answer

Protium


70. Which isotope of hydrogen is rarely found in nature?
(a) Protium
(b) Deuterium
(c) Tritium
(d) None of these
Show Answer

Tritium


71. How many neutrons are there in tritium?
(a) 02
(b) 03
(c) 01
(d) None of these
Show Answer

02


Isotopes of Carbon

72. Atomic number of carbon is ————-.
(a) 07
(b) 06
(c) 08
(d) None of these
Show Answer

06


73. Carbon is the first member of ————–.
(a) Group 1
(b) Group 7
(c) Group 4
(d) Group 6
Show Answer

Group 4


74. How many isotopes of carbon are there in nature?
(a) 03
(b) 13
(c) 07
(d) 14
Show Answer

03


75. C -12, C -13 \ and \ C -14 are the isotopes of ————–.
(a) Iodine
(b) Radon
(c) Carbon
(d) none
Show Answer

carbon


76. Number of neutrons in Carbon-14 \ \left(_{14}C^6 \right) is —————.
(a) 7
(b) 8
(c) 9
(d) 10
Show Answer

8


Isotopes of Chlorine

77. Atomic number of chlorine is ——————–.
(a) 17
(b) 6
(c) 1
(d) 3
Show Answer

17


78. Chlorine is the second member of ————-
(a) Group 1
(b) Group 4
(c) Group 7
(d) Group 5
Show Answer

Group 7


79. Group 7is also called ————-
(a) Alkali metals
(b) Halogens
(c) Nobles
(d) none
Show Answer

Halogens


80. How many isotopes of chlorines are there in nature?
(a) 02
(b) 12
(c) 03
(d) 13
Show Answer

02


81. Cl -35 \ and \ Cl-37 are isotopes of ————–.
(a) Radon
(b) Krypton
(c) Chlorine
(d) Hydrogen
Show Answer

Chlorine


82. The abundance of Cl -35 is —————-.
(a) 75.53%
(b) 53.75%
(c) 73.55%
(d) 53. 66%
Show Answer

75.53%


83. The abundance of Cl-37 is————- in nature.
(a) 24.47%
(b) 47.24%
(c) 74. 42%
(d) 54.26%
Show Answer

24.47%


84. The number of neutrons in Cl-35 is 18 and Cl-37 is —————-.
(a) 20
(b) 40
(c) 02
(d) 04
Show Answer

20


Isotopes of Uranium

85. Atomic number of uranium is —————.
(a) 82
(b) 92
(c) 28
(d) 29
Show Answer

92


86. How many isotopes of uranium in nature?
(a) 07
(b) 05
(c) 03
(d) 04
Show Answer

03


87. The most abundant isotope of uranium is —————.
(a) U -238
(b) U-235
(c) U-234
(d) U-236
Show Answer

U -238


88. The neutrons quantity in U-238 is ————–.
(a) 142
(b) 146
(c) 143
(d) 145
Show Answer

146


Uses of Isotopes

89. Iodine -131 is used for the cure of ————-.
(a) Pneumonia
(b) Cancer
(c) Goiter
(d) None of these
Show Answer

Goiter


90. Cobalt -60 is used for the treatment of —————-.
(a) Cancer
(b) Diarrhea
(c) Tumor
(d) Treat less
Show Answer

Cancer


91. Carbon -14 is used to trace the path of carbon in ————–.
(a) Respiration
(b) Photosynthesis
(c) Reduction
(d) None of these
Show Answer

Photosynthesis


92. Californium -252 is used to inspect airplane luggage for hidden —————-.
(a) Explosives
(b) Smoke detectors
(c) Carbon tracing
(d) None of these
Show Answer

Explosives


Review Exercise Chapter 2

93. The maximum number of electrons in third energy level is:
(a) 10
(b) 32
(c) 18
(d) 64
Show Answer

18


94. Mass of an atom is mostly due to its
(a) Nucleus
(b) Neutrons
(c) Electrons
(d) Protons
Show Answer

Nucleus


95. If Rutherford had used neutrons instead of alpha particles in his scattering experiment, the neutrons would
(a) Not deflect because they have no charge
(b) Have deflected more often
(c) Have been attracted to the nucleus easily
(d) Have given the same results
Show Answer

Not deflect because they have no charge


96. Electron in its ground state does not
(a) Spin
(b) Revolve
(c) Radiate energy
(d) Reside in orbit
Show Answer

Radiate energy


97. Which statement about _6^{12}X \ and \ _6^{14}Y is false except
(a) They are isotopes
(b) They are the same elements
(c) They have the same number of electrons
(d) They have the same number of neutrons
Show Answer

They have the same number of electrons


98. The neutron particle
(a) Has a mass equal to that of an electron
(b) Has a mass approximately equal to that of a proton
(c) Has charge equal to but opposite to that of an electron
(d) Has a positive charge
Show Answer

Has a mass approximately equal to that of a proton


99. Isotopes of the same element have
(a) The same number of protons
(b) The same number of neutrons
(c) Different number of electrons
(d) The same mass number
Show Answer

The same number of protons


100. Which one is the lightest?
(a) An alpha particle
(b) A hydrogen atom
(c) An electron
(d) A proton
Show Answer

An electron


101. The nucleus of an atom has all of the following Characteristics except that
(a) Is positively charged
(b) Is very dense
(c) Contains nearly all of the atom’s mass
(d) Contains nearly all of the atom’s volume
Show Answer

Contains nearly all of the atom’s volume


102. L – shell has sub – shell (s)
(a) s
(b) s and p
(c) s, p, and d
(d) s, p, d and f
Show Answer

s and p


Chemistry Class 9 MCQs (All Chapters)


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