Introduction:
‘Atomic Theory’ explains the structure and behavior of matter by stating that all substances are made up of tiny particles called ‘Atoms’. The earliest scientific atomic theory was proposed by John Dalton in the early 19th century. According to John Dalton, atoms are indivisible, indestructible, and identical for a given element. Later discoveries showed that atoms contain smaller particles such as protons, neutrons, and electrons. Scientists like J.J. Thomson, Ernest Rutherford, and Niels Bohr refined the theory by explaining atomic structure and energy levels.
Here are 50+ MCQs About Atomic Theory:
Q.1 ‘Atomic Theory’ of matter was given by whom?
A) J.J Thomson
B) Enrico Fermi
C) John Dalton
D) Niels Bohr
Answer: C) John Dalton
Q.2 Who discovered the ‘Electron’?
A) Ernest Rutherford
B) J.J Thomson
C) Niels Bohr
D) James Chadwick
Answer: B) J.J Thomson, 1897
Q.3 Which experiment led to the discovery of the nucleus?
A) Cathode ray experiment
B) Oil drop experiment
C) Gold foil experiment
D) Photoelectric experiment
Answer: C) Gold foil experiment
Q.4 Who proposed the ‘Nuclear Model of the Atom’?
A) J.J Thomson
B) Niels Bohr
C) Ernest Rutherford
D) John Dalton
Answer: C) Ernest Rutherford, 1911
Q.5 Which subatomic particle has a negative charge?
A) Proton
B) Neutron
C) Electron
D) Positron
Answer: C) Electron
Q.6 Which subatomic particle has no charge?
A) Proton
B) Electron
C) Neutron
D) Positron
Answer: C) Neutron
Q.7 Who discovered the ‘Neutron’?
A) J.J Thomson
B) Ernest Rutherford
C) James Chadwick
D) Niels Bohr
Answer: C) James Chadwick, 1932
Q.8 The mass of an atom is mainly concentrated in which part?
A) Electron cloud
B) Nucleus
C) Valence shell
D) Orbit
Answer: B) Nucleus
Q.9 Which particle determines the atomic number of an element?
A) Neutron
B) Proton
C) Electron
D) Nucleus
Answer: B) Proton
Q.10 Atomic number is equal to the number of?
A) Neutrons
B) Protons
C) Protons + Neutrons
D) Electrons + Neutrons
Answer: B) Protons
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Q.11 Which scientist is known as the ‘Father of Atomic Theory’?
A) Ernest Rutherford
B) Niels Bohr
C) John Dalton
D) J.J Thomson
Answer: C) John Dalton
Q.12 Which model is known as the ‘Plum Pudding Model’?
A) Rutherford model
B) Bohr model
C) Dalton model
D) Thomson model
Answer: D) Thomson model
Q.13 Who proposed quantized energy levels in atoms?
A) Ernest Rutherford
B) Niels Bohr
C) John Dalton
D) James Chadwick
Answer: B) Niels Bohr
Q.14 ‘Bohr’s model’ is applicable mainly to which atom?
A) Oxygen
B) Hydrogen
C) Helium
D) Carbon
Answer: B) Hydrogen
Q.15 Which force holds protons together in the nucleus?
A) Gravitational force
B) Electrostatic force
C) Nuclear force
D) Magnetic force
Answer: C) Nuclear force
Q.16 Isotopes are atoms having the same:
A) Mass number
B) Atomic number
C) Number of neutrons
D) Atomic mass
Answer: B) Atomic number
Q.17 Isobars have the same:
A) Atomic number
B) Number of electrons
C) Mass number
D) Chemical properties
Answer: C) Mass number
Q.18 Isotones have the same number of:
A) Protons
B) Electrons
C) Neutrons
D) Orbits
Answer: C) Neutrons
Q.19 Which among the following particle was discovered first?
A) Proton
B) Electron
C) Neutron
D) Positron
Answer: B) Electron
Q.20 The charge on a proton is:
A) −1
B) 0
C) +1
D) +2
Answer: C) +1
Also Read:
50 Gk MCQs About Periodic Table
Q.21 What is the maximum number of electrons K-shell have?
A) 2
B) 8
C) 18
D) 32
Answer: A) 2
Q.22 What is the maximum number of electrons L-shell have?
A) 2
B) 8
C) 18
D) 32
Answer: B) 8
Q.23 What is the outermost shell called?
A) K-shell
B) L-shell
C) M-shell
D) Valence shell
Answer: D) Valence shell
Q.24 Which particles revolve around the nucleus?
A) Protons
B) Neutrons
C) Electrons
D) Positrons
Answer: C) Electrons
Q.25 Which scientist introduced the concept of orbits?
A) John Dalton
B) J.J Thomson
C) Ernest Rutherford
D) Niels Bohr
Answer: D) Niels Bohr
Q.26 Which model could not explain line spectra?
A) Bohr model
B) Quantum model
C) Rutherford model
D) Modern model
Answer: C) Rutherford model
Q.27 Which experiment disproved J.J Thomson’s model?
A) Oil drop experiment
B) Gold foil experiment
C) Photoelectric experiment
D) Cathode ray experiment
Answer: B) Gold foil experiment
Q.28 What is the SI unit of atomic mass?
A) Gram
B) Kilogram
C) Atomic mass unit
D) Mole
Answer: B) Kilogram (Kg)
Q.29 Which scientist measured the charge of an electron?
A) Ernest Rutherford
B) Robert A. Millikan
C) Niels Bohr
D) James Chadwick
Answer: B) Robert A. Millikan
Q.30 ‘Oil drop Experiment’ was performed by whom?
A) J.J Thomson
B) Robert A. Millikan
C) Ernest Rutherford
D) John Dalton
Answer: B) Robert A. Millikan
Also Read:
30+ Gk Question and Answer About Chemistry
Q.31 Which atomic model explains atomic spectra?
A) Dalton model
B) Thomson model
C) Rutherford model
D) Bohr atomic model
Answer: D) Bohr atomic model
Q.32 The nucleus of an atom contains:
A) Electrons only
B) Protons only
C) Protons and neutrons
D) Neutrons only
Answer: C) Protons and neutrons
Q.33 Which subatomic particle has the least mass?
A) Proton
B) Neutron
C) Electron
D) Positron
Answer: C) Electron
Q.34 Which element has only one electron?
A) Helium
B) Hydrogen
C) Lithium
D) Oxygen
Answer: B) Hydrogen
Q.35 The valency of an element depends on:
A) Atomic number
B) Mass number
C) Valence electrons
D) Neutrons
Answer: C) Valence electrons
Q.36 Which shell is filled first?
A) L-shell
B) M-shell
C) K-shell
D) N-shell
Answer: C) K-shell
Q.37 Which rules states electrons fill lowest energy levels first?
A) Hund’s rule
B) Aufbau principle
C) Pauli exclusion principle
D) Octet rule
Answer: B) Aufbau principle
Q.38 Which principle states no two electrons have same quantum numbers?
A) Aufbau principle
B) Hund’s rule
C) Pauli exclusion principle
D) Octet rule
Answer: C) Pauli exclusion principle
Q.39 Which model failed to explain atomic stability?
A) Dalton model
B) Bohr model
C) Rutherford model
D) Quantum model
Answer: C) Rutherford model
Q.40 The charge on an electron is measured in:
A) Joule
B) Coulomb
C) Watt
D) Volt
Answer: B) Coulomb (C)
Q.41 Who gave the concept of energy quanta?
A) Albert Einstein
B) Max Planck
C) Niels Bohr
D) Werner Heisenberg
Answer: B) Max Planck
Q.42 Which subatomic particle was discovered by Ernest Rutherford?
A) Electron
B) Neutron
C) Proton
D) Positron
Answer: C) Proton, 1919
Q.43 Atomic mass unit (amu) is based on:
A) Hydrogen atom
B) Oxygen atom
C) Carbon-12 atom
D) Helium atom
Answer: C) Carbon-12 atom
Q.44 The modern atomic theory was given by whom?
A) John Dalton
B) Niels Bohr
C) Erwin Schrödinger
D) Ernest Rutherford
Answer: A) John Dalton
Q.45 Wave mechanical model is also known as:
A) Quantum model
B) Nuclear model
C) Planetary model
D) Plum pudding model
Answer: A) Quantum model
Q.46 Who proposed the wave equation of electrons?
A) Werner Heisenberg
B) Erwin Schrödinger
C) Niels Bohr
D) Max Planck
Answer: B) Erwin Schrödinger
Q.47 Which principle states uncertainty in position and momentum?
A) Pauli principle
B) Aufbau principle
C) Werner Heisenberg uncertainty principle
D) Hund’s rule
Answer: C) Werner Heisenberg uncertainty principle
Q.48 Electrons occupy regions called:
A) Orbits
B) Shells
C) Atomic Orbitals
D) Orbital Rings
Answer: C) Atomic Orbitals
Q.49 Which orbital has spherical shape?
A) p-orbital
B) d-orbital
C) s-orbital
D) f-orbital
Answer: C) S-orbital
Q.50 p-orbitals have how many orientations?
A) 1
B) 2
C) 3
D) 5
Answer: C) 3
Q.51 Maximum how many electrons are there in an orbital?
A) 1
B) 2
C) 4
D) 6
Answer: B) 2
Q.52 Which number denotes energy level?
A) Azimuthal quantum number
B) Spin quantum number
C) Principal quantum number
D) Magnetic quantum number
Answer: C) Principal quantum number
Q.53 Which scientist explained ‘Photoelectric Effect’?
A) Isaac Newton
B) Albert Einstein
C) Niels Bohr
D) Max Planck
Answer: B) Albert Einstein
Q.54 What is the shape of p-orbital?
A) Spherical
B) Dumbbell
C) Circular
D) Linear
Answer: B) Dumbbell
Q.55 Which force binds electrons to nucleus?
A) Nuclear force
B) Gravitational force
C) Electrostatic force
D) Magnetic force
Answer: C) Electrostatic force
Conclusion:
‘Atomic Theory’ has played a crucial role in understanding the nature of matter and the fundamental building blocks of the universe. From Dalton’s simple concept of indivisible atoms to the modern quantum mechanical model, the theory has continuously evolved with scientific discoveries. Each modification improved our knowledge of atomic structure, behaviour, and interactions. Thus, Atomic Theory remains one of the most important scientific theories, helping us explain both everyday phenomena and complex processes at the atomic level.
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