Download CBSE MCQs for Class 9 Science: Chapter 04 Structure of the Atom
Access targeted multiple-choice questions for Chapter 04 Structure of the Atom designed to align with the latest CBSE academic syllabus for Class 9 Science. These objective practice sets help students evaluate their conceptual understanding and improve exam readiness.
Chapter-wise Objective Questions: Chapter 04 Structure of the Atom
View or download the dedicated Chapter 04 Structure of the Atom MCQ resource below. Practicing these 50 objective questions regularly builds familiarity with standard exam patterns and helps secure higher marks in final Science evaluations.
Question: In a neutral atom, the number of protons is equal to
(a) half the number of electrons
(b) number of electrons
(b) number of electrons
(c) number of neutrons
(d) number of neutrons + number of electrons
(d) number of neutrons + number of electrons
Answer: B
Question: 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
(b) 1/12 th mass of hydrogen atom
(c) 1/12 th mass of oxygen atom
(d) 1/12 th mass of helium atom
(d) 1/12 th mass of helium atom
Answer: A
Question: Neutrons were discovered by
(a) Joseph Thomson
(b) James Chadwick
(b) James Chadwick
(c) Ernest Rutherford
(d) John Dalton
(d) John Dalton
Answer: B
Question: Mass of neutron is equal to
(a) that of an electron
(b) half the mass of an electron
(b) half the mass of an electron
(c) the mass of a proton
(d) half the mass of a proton
(d) half the mass of a proton
Answer: C
Question: The mass number of an element is the sum of the numbers of
(a) protons and electrons
(b) electrons and neutrons
(b) electrons and neutrons
(c) protons, electrons and neutrons
(d) protons and neutrons
(d) protons and neutrons
Answer: D
Question: The mass number of an element is denoted by
(a) A
(b) Z
(b) Z
(c) X
(d) N
(d) N
Answer: A
Question: The element with the same atomic and mass number is
(a) oxygen
(b) hydrogen
(b) hydrogen
(c) helium
(d) carbon
(d) carbon
Answer: B
Question: In the periodic table, the elements are arranged in the
(a) increasing order of atomic mass
(b) decreasing order of atomic number
(b) decreasing order of atomic number
(c) alphabetical order
(d) increasing order of atomic number
(d) increasing order of atomic number
Answer: D
Question: The symbol of the element sodium is
(a) Si
(b) S
(b) S
(c) Na
(d) N
(d) N
Answer: C
Question: K is the symbol of
(a) potassium
(b) calcium
(b) calcium
(c) krypton
(d) aluminium
(d) aluminium
Answer: A
Question: The element with the same atomic number and mass number is
(a) Oxygen
(b) Hydrogen
(b) Hydrogen
(c) Helium
(d) Carbon
(d) Carbon
Answer: B
Question: The e/m ratio of an electron for all types of substances is
(a) constant
(b) less than one
(b) less than one
(c) greater than one
(d) zero
(d) zero
Answer: A
Question: A proton is identical to
(a) the nucleus of berellium
(b) the nucleus of helium
(b) the nucleus of helium
(c) a molecule of a hydrogen
(d) an atom of hydrogen
(d) an atom of hydrogen
Answer: A
Question: An particle is
(a) a hydrogen molecule
(b) a helium nucleus
(b) a helium nucleus
(c) an electron
(d) a proton
(d) a proton
Answer: A
Question: 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
(b) the number of neutrons in one atom
(c) the valency of the element
(d) the number of protons in one atom
(d) the number of protons in one atom
Answer: D
Question: The value of e/m of an electron was measured by
(a) Millikan
(b) J.J. Thomson
(b) J.J. Thomson
(c) Dalton
(d) Rutherford
(d) Rutherford
Answer: B
Question: 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
(b) 11, 12, 11
(c) 12, 11, 11
(d) 23, 11, 23
(d) 23, 11, 23
Answer: D
Question: The number of electrons in the outer shell of the most stable or inert atoms is
(a) 1
(b) 4
(b) 4
(c) 6
(d) 8
(d) 8
Answer: A
Question: Which of the following pairs are isotopes?
(a) Oxygen and ozone
(b) Ice and steam
(b) Ice and steam
(c) Nitric oxide and nitrogen dioxide
(d) Hydrogen and deuterium
(d) Hydrogen and deuterium
Answer: A
Question: An atom which has a mass number of 14 and has 8 neutrons is an
(a) isotope of oxygen
(b) isobar of oxygen
(b) isobar of oxygen
(c) isotope of carbon
(d) isobar of carbon
(d) isobar of carbon
Answer: D
Question: Which of the following has an equal number of neutrons and protons?
(a) Hydrogen
(b) Deuterium
(b) Deuterium
(c) Fluorine
(d) Chlorine
(d) Chlorine
Answer: D
Question: Members of which of the following have similar chemical properties?
(a) Isotope
(b) Isobars
(b) Isobars
(c) Allotropes
(d) Both isotopes and allotropes
(d) Both isotopes and allotropes
Answer: C
Question: 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
(b) 36
(c) 30
(d) 56
(d) 56
Answer: B
Question: For an element with atomic number 19, the 19th electron will occupy
(a) L-shell
(b) M-shell
(b) M-shell
(c) N-shell
(d) K-shell
(d) K-shell
Answer: A
Question: The number of electrons in an element with atomic number X and atomic mass Y will be
(a) X – Y
(b) Y – X
(b) Y – X
(c) X + Y
(d) X
(d) X
Answer: C
Question: A natural phenomenon that supports the experimental conclusion that atoms are divisible is
(a) allotropy
(b) radioactivity
(b) radioactivity
(c) cracking
(d) none of these
(d) none of these
Answer: C
Question: 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
(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
Answer: A
Question: 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
(a) 18 Ar40,20 Ca40,
(b) 19 K39 , 19+[K+]39
(c) 18 Ar40,19 K39
(d) 18 Ar40,19 K39 ,20 Ca40
Answer: A
Question: 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: 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+
Answer: A
Question: Which of the following does not have one electron in its valance shell
(a) Na
(b) Ca
(c) Li
(d) H
Question: Which of the following does not have one electron in its valance shell
(a) Na
(b) Ca
(c) Li
(d) H
Answer: B
Question: Which of the following does not have 8 valence electrons:
(a) He
(b) Ne
(c) Ar
(d) Cl
Question: Which of the following does not have 8 valence electrons:
(a) He
(b) Ne
(c) Ar
(d) Cl
Answer: A
Question: 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
(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
Answer: A
Question: 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: 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
Answer: A
Question: 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: 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
Answer: A
More Questions...........................
Question: Composition of the nuclei of two atomic species are given:
X Y
P
P
7 8
N 9 8
(a) 16,16; 1sobars
(b) 16,16; isotopes
(c) 17,15; isotopes
(d) 17,15; isotopes
(a) 16,16; 1sobars
(b) 16,16; isotopes
(c) 17,15; isotopes
(d) 17,15; isotopes
Answer: A
Question: Which of the following are positively charged ions:
Question: Which of the following are positively charged ions:
Atoms Protons Electrons Neutrons
A 17 17 18
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
(b) A and B
(c) C and D
(d) D and F
Answer: A
Question: 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: 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
Answer: A
Question: Which of the following is correct?
Column 1 Column 2
Question: 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
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
Answer: A
Question: 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: 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
Answer: A
Question: 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: 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
Answer: A
Question: Who discovered the electron?
(a) Rutherford
(b) Chadwick
(c) Thomson
(d) Goldstein
(a) Rutherford
(b) Chadwick
(c) Thomson
(d) Goldstein
Answer : C
Question: 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: 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
Answer : A
Question: 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: The isotope used to remove the brain tumours and treatment of cancer is
(a) U-235
(b) Na-24
(c) Iodine
(d) C0-60
Answer : D
Question: The nucleons are
(a) Protons and electrons
(b) Neutrons and electrons
(c) Protons and neutrons
(d) None of these
Question: The nucleons are
(a) Protons and electrons
(b) Neutrons and electrons
(c) Protons and neutrons
(d) None of these
Answer : C
Question: How many electrons in a Hydrogen (H) atom:
(a) One
(b) Two
(c) Three
(d) Four
Question: How many electrons in a Hydrogen (H) atom:
(a) One
(b) Two
(c) Three
(d) Four
Answer : A
Question: The atomic number of the element with maximum number of unpaired electrons is:
(a) 23
(b) 33
(c) 15
(d) 26
Question: The atomic number of the element with maximum number of unpaired electrons is:
(a) 23
(b) 33
(c) 15
(d) 26
Answer : D
Question: 13Al27 is a stable isotope. 13Al29 is expected to disintegrate by:
a.α emission
(b) β emission
(c) Positron emission
(d) Proton emission
Answer : B
Question: 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: The atomic number of an element having mass number 23 and number of neutron 12 is ________.
(a) 23
(b) 11
(c) 12
(d) 35
Answer: B
Question: 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
Answer : A
Question: 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
(a) Size of an element
(b) Valency of an element
(c) Molar mass of the element
(d) None of these
Answer. B
Question: 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
(a) P-32
(b) I-131
(c) Co-60
(d) any of these
Answer : A
Question: 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: 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
Answer : D
Question: 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: 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
Answer : A 
Question: 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
Answer : C
Question: Which of the following are positively charged ions:
(a) A and B
(b) C and D
(c) B and D
(d) D and F
Answer : C
Question: 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
Answer : D
Question: 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.
Answer : B
Question: 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
Answer : C
Question: 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
(b) H2
(c) He
(d) Ar
Answer : B
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Practice MCQs for Class 9 Science Chapter 04 Structure of the Atom
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Where can I access latest CBSE Class 9 Science Structure of the Atom MCQs Set 02?
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