Class 9 Science Chapter 4 Atoms and Molecules MCQ Questions with Answer

Structure of Atom Class 9 MCQ is one of the best strategies to prepare for the CBSE Class 9 Board exam. If you want to complete a grasp concept or work on one’s score, there is no method except constant practice. Students can improve their speed and accuracy by doing more Structure of Atom class 9 MCQ which will help them all through their board test.

Structure of Atom Class 9 MCQ Questions with Answer

Class 9 Science MCQ with answers are given here to Chapter 4 Structure of Atom. 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 Structure of Atom 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 Structure of Atom MCQ with answers given below.

Question 1: Amongst element X (2,8,6) and (2,8,8) which is more reactive and why ?
(A) X because it is a metal
(B) Y because it is non metal
(C) X because it has 6 valence electrons
(D) Y because it is gas 

Question 2: Cathode rays have
(A) Mass only
(B) Charge only
(C) Both mass and charge
(D) Neither mass nor charge

Question 3: Which of these is a pairs isobar ?
(A) 6C12, 8O16
(B) 6C13, 6C14
(C) 20Ca40, 18Ar40
(D) None of these

Question 4:  The electronic configuration of the element with atomic number 19 is
(A) 2,8,7
(B) 2,9,8
(C) 2,8,8,1
(D) 2,10,7 

Question 5:  The valence electrons of an element are reponsible for
(A) Physical properties of an element
(B) Chemical properties of an element
(C) Both the properties
(D) None of these 

Question 6: An element has electronic configuration 2,8,4 it will be classified as
(A) Metal
(B) Non metal
(C) Metalloid
(D) None of these

Question 7: Isotopes of an element do not have
(A) Same number of element
(B) Same physical properties
(C) Same chemical properties
(D) Same elecrical charge on the nucleus

Question: 8 Isotopes differ in
(A) No. of electrons
(B) No. of protons
(C) No. of neutrons
(D) Chemical reactivity 

Question 9: The atomic number of an element ‘y’ is 20. The electronic configuration of the ion having inert gas configuration is
(A) 2,8,10
(B) 2,18
(C) 2,10,8
(D) 2,8,8 

Question 10: Which amonght the following statement is true?
(A) a rays are cathode rays
(B) Electrons make up the cathode rays
(C) Protons make up the cathode rays
(D) Electron magnetic radiation make up the cathode rays

Question 11: 7N15 and 8O16 are a pair of
(A) Isotopes
(B) Isobars
(C) Isotones
(D) None of these 

Question 12: The nucleus of the hydrogen atom is called as
(A) Neutron
(B) Electron
(C) Proton
(D) Nucleons 

Question 13: The e/m value for cathode rays
(A) varies with the nature of the gas
(B) does not vary with the nature of gas
(C) could not be determinde by J.J. Thomson
(D) Both (B) & (C) are correct 

Question 14: Cathode raysget deflected in a electric field towards
(A) Positive plate
(B) Negative Plate
(C) No deflection takes place
(D) First towards negative plate and then towards positive plate 

Question 15: The relative atomic masses of many elements are not whole numbers because
(A) They can’t be determined very accurately
(B) The atoms ionize during the determination
(C) of the existence of isotopes
(D) of the presence of impurities

Question 16: The energy associated with an orbit
(a) increases with his distance from the nucleus
(b) decreases with increase in the distance from nucleus
(c) remains constant whatever may be the distance
(d) none of these   

Question 17:  The orbits are numbered by
(a) 100, 200, 300….
(b) 10, 20, 30….
(c) 1, 2, 3, 4….
 (d) 5, 10, 15….

Question 18: The isotope of hydrogen that contains the same numer of protons and neutrons in its nucleus is called
(A) Protium
(B) Deutrium
(C) Tritium
(D) None of these 

Question 19: a particle is emitted by 92X238 during redioactivity. The new specie y should be :
(A) 90Y234
(B) 90Y238
(C) 92Y234
(D) 94Y234 

Question 20: When an a-particle is emitted
(A) Element moves 2 places to the right in the periodic table
(B) Element moves one place to the left
(C) Element moves 2 places to the left in the periodic table
(D) Elements maintains its position

Question 21 : If the nuclide of actinium 89Ac228, emits b particle, the daughter nuclide will be
(A) 88Ra228
(B) 90Th228
(C) 87Fr224
(D) 90Th229

Question 22:  The distribution of _____ in various orbits of an atom is called electronic configuration of element
(a) neutrons
(b) protons
(c) electrons
(d) all of these 

Question 23:  The electronic configuration of oxygen
(a) 2, 7
(b) 2, 6
(c) 2, 4, 2
(d) 4, 4 

Question 24:  2, 8,1 is the electronic configuration of
(a) lithium
(b) potassium
(c) helium
(d) sodium 

Question 25 :  The shells or orbits are denoted by
(a) K, L, M, N,…..
(b) a, b, c, d,….
(c) A, B, C, d,….
(d) V, W, X, Y, Z,….

Question 26 :  The shell which has two electrons is
(a) first shell
(b) second shell
(c) third shell
(d) fourth shell

Question 27:  Maximum number of electrons, the third shell can accommodate is
(a) 32
(b) 2
(c) 8 
(d) 18 

Question 28:  In general, the nth shell can accommodate_____ electrons where ‘n’ stands for number of the shell.
(a) 3n^₂ 
(b) 2n²
(c) n² 
(d) 2n 

Question 29:  In a chemical reaction, ___________ participate.
(a) valence electrons
(b) all electrons of the atom
(c) protons
(d) electrons and protons

Question 30: The valency of an element is its
(a) electronic configuration
(b) combining capacity
(c) atomic number
(d) mass number

Question 31:  Number of electrons in the outermost shell of carbon is
(a) 4
(b) 6
(c) 3
(d) 8 

Question 32:  Total number of electrons in an atom of nitrogen is
(a) 9
(b) 6
(c) 8
(d) 7 

Question 33:  The noble gases from the following are
(a) O_2, N₂, H₂ 
(b) Cl, F, Br
(c) He, Ne, Ar
(d) Na, K, Ca

Question 34:  Noble gases do not react with other elements to form compounds because
(a) they are unstable
(b) they are gases
(c) they are stable
(d) they are already compounds

Question 35: . The number of electrons shared by each chlorine atom to form a molecule is
(a) 2
(b) 1
(c) 3
(d) 7 

Question 36:  In a CO₂ molecule, the total number of electrons shared between a carbon and two oxygen atoms are
(a) 8
(b) 4
(c) 2
(d) 6

Question 37:  In the formation of NaCl, sodium atom
(a) receives an electron
(b) shares an electron
(c) does not react
(d) donates an electron 

Question 38:  Atoms combine to attain stable configuration by
(a) sharing electrons
(b) sharing, accepting or donating electrons
(c) donating electrons
(d) accepting electrons

Question 39 :  A chlorine atom has ____ protons, _____ electrons and _____ neutrons.
(a) 18, 17, 18
(b) 17, 18, 18
(c) 17, 17, 18
(d) 17, 17, 17 

Question 40 :  The number of electrons shared between two oxygen atoms is
(a) 2
(b) 1
(c) 2
(d) 4 

Question 41 :  Compound formed by sharing electrons is called

(a) ionic compound
(b) electrovalent compound

(c) covalent compound
(d) coordinate compound

Question 42 :  Cations are carry

(a) both positive and negative charges
(b) neutral charge

(c) negative charge
(d) positive charge

Question 43 :  Mg →Mg²⁺ ______

(a) 2 electrons
(b) 1 electrons

(c) no electrons
(d) 2 protons 

Question 44 :  Sodium ion (Na+) has ____ number of electrons
(a) 10
(b) 12
(c) 11
(d) 13 

Question 45:  When chlorine atom becomes chloride ion it
(a) loses an electron gains an electron
(b) gains an electron
(c) electrostatic force
(d) magnetic force

Question 46 :  Sodium and chlorine atoms are held together in NaCl by

(a) electromagnetic force
(b) gravitational force

(c) electrostatic force
(d) magnetic force 

Question 47:  An atom that becomes charged by gaining or losing an electron is called

(a) cation
(b) anion

(c) ion
(d) electron

Question 48 : The scientist who measured the mass and charge of an electron was

(a) Goldstein
(b) Rutherford

(c) Dalton
(d) Thomson

Question 49 : The mass of an electron is

(a) 1837 times the mass of proton
(b)1/1837 th times the mass of hydrogen atom

(c)1/1831 th times the mass of oxygen atom
(d)1/1837 th times the mass of carbon atom

Question 50 : The mass of proton is about the same as that of

(a) carbon atom
(b) an electron

(c) hydrogen ion
(d) oxygen atom 

Question 51 : Rutherford directed a stream of _____ on a thin gold leaf in the scattering experiment

(a) alpha particles
(b) beta particles

(c) gamma particles
(d) X-rays 

Question 52: Based on his experiments, Rutherford concluded that the positive charge of an atom is

(a) spread all over the atom
(b) revolves around the atom in orbits

(c) exists in the empty space
(d) present in the nucleus

Question 53:  An aluminium ion carries _____ units of positive charge

(a) 2
(b) 3

(c) 1
(d) 4

Question 54 :  Oxygen atom becomes an oxide ion by

(a) losing two electrons
(b) gaining two electrons

(c) gaining one electron
(d) losing one electron

Question 55 : The scientist who put forward the atomic theory in 1808 was

(a) Dalton
(b) Lavoiser

(c) Galileo
(d) Thomson 

Question 56 : According to the atomic theory

(a) matter is not created but can be destroyed in a chemical reaction.

(b) matter is neither created nor destroyed in a chemical reaction

(c) matter is created but not destroyed in a chemical reaction

(d) matter can be created and destroyed in a chemical reaction 

Question 57 : Which of the following statement is true?

(a) Elements combine in fixed proportion by volume to form compounds

(b) Elements combine in fixed proportions by weights to form compounds

(c) elements combine in fixed proportion by mass to form compounds

(d) None of these

Question 58 : Mass of neutron is equal to

(a) that of an electron
(b) half the mass of an electron

(c) the mass of a proton
(d) half the mass of a proton

Question 59: The mass number of an element is the sum of the numbers of

(a) protons and electrons
(b) electrons and neutrons

(c) protons, electrons and neutrons
(d) protons and neutrons 

Question 60 : Atomic number of an atom is the

(a) number of protons + number of neutrons
(b) number of neutrons

(c) number of electrons + number of protons
(d) number of protons

Question 61 : Atomic number of an element is denoted by

(a) X
(b) A

(c) Z
(d) N

Question 62 : In a neutral atom, the number of protons is equal to

(a) half the number of electrons
(b) number of electrons

(c) number of neutrons
(d) number of neutrons + number of electrons

Question 63 : Atomic mass of an element is the number of times by which the mass of its atom is greater than

(a) 1/12 th mass of carbon atom
(b) 1/12 th mass of hydrogen atom

(c) 1/12 th mass of oxygen atom
(d) 1/12 th mass of helium atom 

Question 64: Neutrons were discovered by

(a) Joseph Thomson
(b) James Chadwick

(c) Ernest Rutherford
(d) John Dalton 

Question 65 : K is the symbol of

(a) potassium
(b) calcium

(c) krypton
(d) aluminium

Question 66 : The element with the same atomic number and mass number is

(a) Oxygen
(b) Hydrogen

(c) Helium
(d) Carbon

Question 67 : The mass number of an element is denoted by

(a) A
(b) Z

(c) X
(d) N 

Question 68 : The element with the same atomic and mass number is

(a) oxygen
(b) hydrogen

(c) helium
(d) carbon

Question 69 : In the periodic table, the elements are arranged in the

(a) increasing order of atomic mass
(b) decreasing order of atomic number

(c) alphabetical order
(d) increasing order of atomic number

Question 70 : The symbol of the element sodium is

(a) Si
(b) S

(c) Na
(d) N

Question 71 : In the periodic table, the elements are arranged in the

(a) Increasing order of atomic mass
(b) Decreasing order of atomic number

(c) Alphabetical order
(d) Increasing order of atomic number

Question 72 : In a neutral atom, the number of protons is equal to

(a) Number of electrons
(b) Half the number of electrons

(c) Number of neutrons
(d) Number of electrons and neutrons

Question 73 : The mass number of an element is denoted by

(a) A
(b) Z

(c) X
(d) N 

Question 74 : The mass of an electron is

(a) 1837 times the mass of proton
(b) 1/1837th times the mass of oxygen atom

(c) 1/1837th times the mass of carbon atom
(d) 1/1837th times the mass of hydrogen atom 

Question 75 : The scientist who put forward the atomic theory in 1808 was

(a) Dalton
(b) Lavoiser

(c) Galileo
(d) Thomson

Question 76: The mass number of an element is the sum of the number of

(a) Proton and electron
(b) Electron and neutrons

(c) Protons, electrons and neutrons
(d) Protons and neutrons

Question 77 : Rutherford directed a stream of __________on a thin Gold leaf in the scattering experiment

(a) Alpha particle
(b) Beta particle

(c) Gamma particle
(d) X-rays

Question 78 : The value of e/m of an electron was measured by

(a) Millikan
(b) J.J. Thomson

(c) Dalton
(d) Rutherford 

Question 79 : The atomic number of an element is 11 and its mass number is 23. The respective number of electrons, protons and neutrons in this atom will be

(a) 11, 11, 12
(b) 11, 12, 11

(c) 12, 11, 11
(d) 23, 11, 23 

Question 80: The number of electrons in the outer shell of the most stable or inert atoms is

(a) 1
(b) 4

(c) 6
(d) 8

Question 81 : The e/m ratio of an electron for all types of substances is

(a) constant
(b) less than one

(c) greater than one
(d) zero

Question 82 : A proton is identical to

(a) the nucleus of berellium
(b) the nucleus of helium

(c) a molecule of a hydrogen
(d) an atom of hydrogen

Question 83: An particle is

(a) a hydrogen molecule
(b) a helium nucleus

(c) an electron
(d) a proton 

Question 84 : The atomic number of an element is determined by

(a) the number of electrons in one atom
(b) the number of neutrons in one atom

(c) the valency of the element
(d) the number of protons in one atom

Question 85 : An atom of an element has 26 electrons and has a mass number 56. The nucleus of this atom contains ______ neutrons

(a) 26
(b) 36

(c) 30
 (d) 56

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Question 86 : For an element with atomic number 19, the 19th electron will occupy

(a) L-shell
(b) M-shell

(c) N-shell
(d) K-shell

Question 87 : The number of electrons in an element with atomic number X and atomic mass Y will be

(a) X – Y
(b) Y – X

(c) X + Y
(d) X

Question 88: Which of the following pairs are isotopes?

(a) Oxygen and ozone
(b) Ice and steam

(c) Nitric oxide and nitrogen dioxide
(d) Hydrogen and deuterium

Question 89 : An atom which has a mass number of 14 and has 8 neutrons is an

(a) isotope of oxygen
(b) isobar of oxygen

(c) isotope of carbon
(d) isobar of carbon

Question 90: Which of the following has an equal number of neutrons and protons?

(a) Hydrogen
(b) Deuterium

(c) Fluorine
(d) Chlorine

Question 91 : Members of which of the following have similar chemical properties?

(a) Isotope
(b) Isobars

(c) Allotropes
(d) Both isotopes and allotropes

Question 92 : The electronic configuration of Cl- ion is:
(a) 2,8,8
(b) 2,8,7
(c) 2,8,6
(d) 2,8,8,1

Question 93 : Which of the following does not have one electron in its valance shell
(a) Na
(b) Ca
(c) Li
(d) H

Question 94: Which of the following does not have 8 valence electrons:
(a) He
(b) Ne
(c) Ar
(d) Cl

Question 95 : How many electrons, protons and neutrons are present in X+, if atomic number of X is 19 and its mass number is 39
(a) E=19, P=19, N= 20
(b) E=18, P=19, N= 20
(c) E=18, P=19, N= 19
(d) E=19, P=20, N= 20

Question 96 : Which of the following statements does not belong to Bohrs model?
(a) The electrons radiate energy during revolution due to force of attraction between nucleus and electrons
(b) Energy of the electrons in the orbit is quantized
(c) The electrons in the orbit nearest to the nucleus is the lowest energy
(d) Electrons revolve around the nucleus in different orbits having fixed energies

Question 97 : When a gold foil is bombarded by a beam of α particle, only a few of them get deflected whereas most go straight undeflecte This is because
(a) The volume of nucleus is much smaller than that of the atom
(b) The force of attraction exerted on α particles by the electrons is insufficient
(c) The force of repulsion acting on the fast moving α particles is very small
(d) The neutrons have no effect on α particles

Question 98 : The highest value of e/m ratio for anode rays is observed when the discharge tube is filled with:
(a) N₂
(b) H₂
(c) He
(d) Ar

Question 99 : Which of the following statement is correct about proton?
(a) It is an ionized Hydrogen atom
(b) It is the nucleus of deuterium
(c) It is an ionized hydrogen molecule
(d) It is an α particle with unit positive charge

Question 100. The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16

Question 101: Na+ has 12 neutrons and 10 electrons. Which of the following statements is correct?
(a) Na+ has atomic number 11 and mass number 23.
(b) Na+ has atomic number 10 and mass number 22.
(c) Na+ has atomic number 10 and mass number 23.
(d) Na+ has atomic number 11 and mass number 22.

Question 102 : Composition of the nuclei of two atomic species are given:

                                               X                                                                  Y
P                                             

                                               7                                                                   8

N                                             9                                                                   8

(a) 16,16; 1sobars
(b) 16,16; isotopes
(c) 17,15; isotopes
(d) 17,15; isotopes

Question 103 : A natural phenomenon that supports the experimental conclusion that atoms are divisible is

(a) allotropy
(b) radioactivity

(c) cracking
(d) none of these

Question 104 : The number of valence electrons determines:
(a) Chemical properties of elements
(b) Physical properties of elements
(c) Both physical and chemical properties of elements
(d) Neither physical nor chemical properties of elements

Question 105 : Cathode rays have :
(a) Charge only
(b) Mass only
(c) Charge as well as mass
(d) Neither charge nor mass

Question 106 : Which of the following are isobars: 18Ar⁴⁰, 19 K³⁹ ,20 Ca⁴⁰, 19[K⁺]³⁹
(a) 18 Ar⁴⁰,20 Ca⁴⁰,
(b) 19 K³⁹ , 19+[K⁺]³⁹
(c) 18 Ar⁴⁰,19 K³⁹
(d) 18 Ar⁴⁰,19 K³⁹ ,20 Ca⁴⁰

Question 107 : Which of the following are isotopes: 1 ¹ H, 1 ²D,1 ³ T,1 ¹ H+
(a) 1 ¹ H, 1 ²D,1 ³ T
(b) 1 ¹ H, 1 ¹ H+
(c) 1 ¹ H, 1 ²D,1 ¹ H+
(d) 1 ¹ H, 1 ³ T,1 ¹ H+

Question 108 : The fluorescence on the walls of discharge tube is due to:
(a) Cathode rays
(b) Anode rays
(c) Canal rays
(d) None of the above

Question 109: The isotope used to remove the brain tumours and treatment of cancer is
(a) U-235
(b) Na-24
(c) Iodine
(d) C0-60

Question 110: The nucleons are
(a) Protons and electrons
(b) Neutrons and electrons
(c) Protons and neutrons
(d) None of these

Question 111: How many electrons in a Hydrogen (H) atom:
(a) One
(b) Two
(c) Three
(d) Four

Question 112: The atomic number of the element with maximum number of unpaired electrons is:
(a) 23
(b) 33
(c) 15
(d) 26

Question 113: The electronic configuration of Cl(17) is:
(a) 2,8,7
(b) 2,2, 8,5
(c) 2,8,2,5
(d) 2,2,5,8

Question 114: Which of the following are positively charged ions:

Atoms      Protons         Electrons           Neutrons
   A            17               17                     18

  B             12               10                     12

  C             16               17                     20

  D             1

  E             18              18                     22

  F             10              10                     10

(a) B and D
(b) A and B
(c) C and D
(d) D and F

Question 115: If K, L, M, N shells of an atom are full, the total number of electrons in the atom are:
(a) 60
(b) 26
(c) 42
(d) 36

Question 116: Which of the following is correct?
Column 1                  Column 2

A. Electrons         i. Positive charge
B. Protons           ii. No charge
C. Neutrons        iii. Negative charge
(a) A-iii, B-i, C-ii
(b) A-iii, B-ii, C-i
(c) A-ii, B-iii, C-i
(d) A-ii, B-i, C-iii

Question 117: A student weighs 30kg. Suppose his body is entirely made of electrons. How any electrons are there in his body? Mass of an electron= 9.1X10-31kg
(a) 3.29 X10³¹
(b) 3.29 X10³⁰
(c) 3.29 X10²³
(d) 3.29 X10³²

Question 118 : The charge/ mass ratio of electron:
(a) Remains constant
(b) Depends on the nature of the electrodes
(c) Depends upon nature of the gas
(d) Depends on both nature of the gas and nature of the electrode

Question 119: Who discovered the electron?
(a) Rutherford
(b) Chadwick
(c) Thomson
(d) Goldstein

Question 120: Which of the following isotope is used in the treatment of blood cancer?
(a) P-32
(b) I-131
(c) Co-60
(d) any of these

Question 121 : When alpha-particles are sent through a thin metal foil, most of them go straight through the foil because
(a) alpha-particles are positively charged
(b) alpha-particles are much smaller than electrons
(c) alpha-particles move with low velocity
(d) most part of the atom is empty

Question 122: The electronic configuration of an atom with atomic number 19 is:
(a) 2, 8, 8, 1
(b) 1, 2, 2, 8
(c) 2, 8, 9
(d) 2, 10, 7

Question 123: The charge/ mass ratio of electron:

(a) Depends on the nature of the electrodes

(b) Depends upon nature of the gas
(c) Remains constant

(d) Depends on both nature of the gas and nature of the electrodea

Question 124 : 13Al27 is a stable isotope. 13Al29 is expected to disintegrate by:
a.α emission
(b) β emission
(c) Positron emission
(d) Proton emission

Question 125: The atomic number of an element having mass number 23 and number of neutron 12 is ________.
(a) 23
(b) 11
(c) 12
(d) 35

Question 126 : Isotopes are
(a) atoms of the same element
(b) atoms of different elements
(c) molecules of the same element
(d) radicals of the same element

Question 127: What property of an element determines its chemical behaviour?
(a) Size of an element
(b) Valency of an element
(c) Molar mass of the element
(d) None of these

Question 128 : What property of an element determines its chemical behaviour?
(a) Size of an element
(b) Valency of an element
(c) Molar mass of the element
(d) None of these 

Question 129: Which of the following are positively charged ions:

(a) A and B

(b) C and D

Question 130 : A student weighs 30kg. Suppose his body is entirely made of electrons. How any electrons are there in his body? Mass of an electron= 9.1X10^-31kg

(a) 3.29 X10³¹

(b) 3.29 X10³⁰

(c) 3.29 X10²³

(d) 3.29 X10³²

Question 131 : Which of the following is correct?

   Column 1             Column2

(a) Electrons      i. Positive charge

(b) Protons        ii. No charge

(c) Neutrons     iii. Negative charge

(a) A-iii, B-ii, C-i

(b) A-iii, B-i, C-ii

(c) A-ii, B-iii, C-i

(d) A-ii, B-i, C-iii

Question 132: If K, L, M, N shells of an atom are full, the total number of electrons in the atom are:

(a) 60
(b) 26
(c) 42
(d) 36

(c) B and D

(d) D and F 

Question 133: The electronic configuration of Cl(17) is:

(a) 2,8,7

(b) 2,2, 8,5

(c) 2,8,2,5

(d) 2,2,5,8 

Question 134: Composition of the nuclei of two atomic species are given: 

The mass number of x and Y and their relation is

(a) 16,16; isotopes

(b) 17,15; isotopes

(c) 17,15; isotopes

(d) 16,16; 1sobars

Question 135: Na⁺ has 12 neutrons and 10 electrons. Which of the following statements is correct?

(a) Na⁺ has atomic number 10 and mass number 22.

(b) Na⁺ has atomic number 11 and mass number 23.

(c) Na⁺ has atomic number 10 and mass number 23.

(d) Na⁺ has atomic number 11 and mass number 22.

Question 136: Which of the following statement is correct about proton?

(a) It is the nucleus of deuterium

(b) It is an ionized hydrogen molecule

(c) It is an ionized Hydrogen atom

(d) It is an α particle with unit positive charge

Question 137: The highest value of e/m ratio for anode rays is observed when the discharge tube is filled with:

(a) N₂
(b) H₂
(c) He
(d) Ar

Question 138 : When a gold foil is bombarded by a beam of α particle, only a few of them get deflected whereas most go straight undeflecte(d) This is because

(a) The force of attraction exerted on α particles by the electrons is insufficient

(b) The volume of nucleus is much smaller than that of the atom

(c) The force of repulsion acting on the fast moving α particles is very small

(d) The neutrons have no effect on α particles 

Question 139 : Which of the following statements does not belong to Bohr’s model?

(a) Energy of the electrons in the orbit is quantized

(b) The electrons in the orbit nearest to the nucleus is the lowest energy

(c) Electrons revolve around the nucleus in different orbits having fixed energies

(d) The electrons radiate energy during revolution due to force of attraction between nucleus and electrons

Question 140 : How many electrons, protons and neutrons are present in X⁺, if atomic number of X is 19 and its mass number is 39

(a) E=19, P=19, N= 20

(b) E=18, P=19, N= 20

(c) E=18, P=19, N= 19

(d) E=19, P=20, N= 20

Question 141 : Which of the following does not have 8 valence electrons:

(a) He
(b) Ne
(c) Ar
(d) Cl^–

Question 142: Which of the following does not have one electron in its valance shell

(a) Na
(b) Li
(c) H
(d) Ca 

Question 143: Cathode rays have :

(a) Charge only

(b) Mass only

(c) Charge as well as mass

(d) Neither charge nor mass

Question 144: The number of valence electrons determines:

(a) Physical properties of elements

(b) Chemical properties of elements

(c) Both physical and chemical properties of elements

(d) Neither physical nor chemical properties of elements 

Question 145: Which of the following correctly represents the electronic distribution in the Mg atom?
(a) 3, 8, 1
(b) 2, 8, 2
(c) 1, 8, 3
(d) 8, 2, 2

Question 146 : The electron should be filled in the orbital in accordance with the increasing order of their energy. This statement is related with
(a) Affbau principle
(b) Pauli principle
(c) Hund’s principle
(d) Plank’s rules

Question 147: The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16

Question 148: An neutral element A has 3 electrons, the atomic number of an element is _______.
(a) 1
(b) 2
(c) 5
(d) 3

Question 149 : The isotope deuterium of hydrogen has
(a) No neutrons and one proton
(b) One neutrons and two protons
(c) One electron and two neutron
(d) One proton and one neutron

Question 150: What prevents an atom from being collapsed?
(a) The nuclear forces
(b) Movement of electrons in discrete energy levels
(c) The electron-electron repulsions
(d) All of these

Question 151: Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charge(d)
(ii) Established that the a-particles are four times as heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson’s model.
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) only (i)

Question 152 : What is an electron?
(a) A wave
(b) A particle
(c) Either of two, depending on how it is observed
(d) Neither of these

Question 153: The nucleus of an atom contains:
(a) Protons
(b) Electrons
(c) Protons and neutrons
(d) Neutrons

Question 154 : Which scientist gave the concept of fixed energy levels around the nucleus?
(a) Ernest Rutherford
(b) Neils Bohar
(c) J.J.Thomsan
(d) None of these

Question 155: In an atom, the constituent electrons:
(a) Do not move
(b) Are uniformly distributed
(c) Move around the nucleus in fixed energy levels.
(d) Move around the nucleus in a random way.

Question 156: Which of the following pairs are isotopes?
(a) Oxygen and ozone
(b) Ice and steam
(c) Nitric oxide and nitrogen dioxide
(d) Hydrogen and deuterium

Question 157 :Which of the following has a charge of +1 and a mass of 1 amu?
(a) A neutron
(b) A proton
(c) An electron
(d) A helium nucleus

Question 158 : Members of which of the following have similar chemical properties?
(a) Isotope
(b) Isobars
(c) Allotropes
(d) Both isotopes and allotropes

Question 159: J. J. Thomson was awarded the Nobel Prize for Physics for his work on the discovery of electrons. Which of the following was/were suggested by Thomson in his model of atom?
(a) An atom consists of a positively charged sphere and the electrons are embedded in it.
(b) An atom consists of a negatively charged sphere and the electrons are embedded in it.
(c) The negative and positive charges are equal in magnitude.
(d) Both (1) and (3)

Question 160. Which of the following does not have 8 valence electrons:
(a) He
(b) Ne
(c) Ar
(d) Cl

Question 161 . Which of the following particles was discovered first?
(a) Neutron
(b) Electron
(c) Proton
(d) Meson

Question 162 . Isotopes of an element have:
(a) the same physical properties
(b) different chemical properties
(c) different number of neutrons
(d) different atomic numbers

Question 163. The electron should be filled in the orbital in accordance with the increasing order of their energy. This statement is related with
(a) Affbau principle
(b) Pauli principle
(c) Hund’s principle
(d) Plank’s rules

Answer :  A

(a) Magnesium
(b) Helium
(c) Sodium
(d) Hydrogen

Question 164 . Light energy is treated as a form of matter because it consists of:
(a) Photons or bundles of energy
(b) Electrons or wave like matter
(c) Neutrons
(d) None of the Above

Question 165 : Though the three fundamental particles are present in almost all elements, one element does not possess:
(a) Proton
(b) Neutron
(c) Electron
(d) Nucleons

Question 166 . According to J.J Thomson, an atom is a positively charged sphere. Which sub-atomic particles is embedded in it?
(a) Electrons
(b) Canal Rays
(c) Protons
(d) Neutrons

Question 167 . The smallest fundamental particle, of an atom with unit negative charge is called:
(a) Electron
(b) Proton
(c) Neutron
(d) Alpha-particle

Question 168. Neutron Possesses
(a) Positive charge
(b) No charge
(c) Negative charge
(d) None of the above.

Question 169. Each of the stationary orbits are associated with:
(a) A certain amount of velocity.
(b) A certain amount of mass.
(c) A certain amount of energy.
(d) A certain amount of force.

Question 170. Which of the following is the correct electronic configuration for magnesium?
(a) 2, 8, 1
(b) 2, 8, 3
(c) 2, 8, 4
(d) 2, 8, 2

Question 171. What are the essential conditions for the production of anode rays?
(a) High voltage and low pressure
(b) High voltage and high pressure
(c) Low voltage and high pressure
(d) Low voltage and low pressure

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