Structure of Atom Class 11 MCQ. Multiple choice questions for Class 11 Chemistry on the Structure of Atom chapter, covering key concepts like atomic models and particles.
Structure of Atom Class 11 MCQ topics:
Early Atomic Models and Laws: MCQ 1–9
Discovery of the Electron and its Properties: MCQ 10–18
Discovery of Proton and Neutron: MCQ 19–26
Thomson’s Atomic Model: MCQ 27–30
Rutherford’s Nuclear Model: MCQ 31–37
Atomic Number, Mass Number, Isotopes, and Isobars: MCQ 38–41
Electromagnetic Radiation and Wave Nature of Light: MCQ 42–46
Planck’s Quantum Theory and Photoelectric Effect: MCQ 47–52
Atomic Spectra and Hydrogen Spectrum: MCQ 53–62
Bohr’s Model for Hydrogen Atom: MCQ 63–75
Wave-Particle Duality and Uncertainty Principle: MCQ 76–79
Quantum Numbers and Atomic Orbitals: MCQ 80–88
Principles of Electron Filling (Aufbau, Pauli, Hund): MCQ 89–94
Electronic Configuration of Atoms: MCQ 95–100
Structure of Atom Class 11 MCQ – Online Test
Question 1: Who first proposed the existence of atoms as indivisible particles?
A. John Dalton
B. Niels Bohr
C. Indian and Greek philosophers
D. James Clerk Maxwell
C. Indian and Greek philosophers, around 400 B.C., first proposed atoms as fundamental building blocks of matter.
Question 2: What was the original meaning of the word ‘atom’?
A. Indivisible
B. Visible
C. Complex
D. Energy
A. The word ‘atom’ is derived from the Greek word ‘a-tomio,’ meaning ‘indivisible’ or ‘uncut-able.’
Question 3: Which scientist proposed the atomic theory on a firm scientific basis in 1808?
A. Rutherford
B. Dalton
C. Faraday
D. Bohr
B. John Dalton proposed the atomic theory on a firm scientific basis in 1808.
Question 4: Dalton’s atomic theory helped explain which of the following laws?
A. Law of Conservation of Mass
B. Law of Multiple Proportions
C. Law of Constant Composition
D. All of the above
D. Dalton’s theory explained the Law of Conservation of Mass, the Law of Multiple Proportions, and the Law of Constant Composition.
Question 5: According to Dalton’s Atomic Theory, which law states that matter cannot be created or destroyed in a chemical reaction?
A. Law of Multiple Proportions
B. Law of Constant Composition
C. Law of Conservation of Mass
D. Law of Electromagnetic Radiation
C. The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction.
Question 6: Which law is based on the observation that a chemical compound always contains the same elements in the same proportions by mass?
A. Law of Conservation of Mass
B. Law of Multiple Proportions
C. Law of Constant Composition
D. Law of Definite Proportions
C. The Law of Constant Composition is based on this observation.
Question 7: The Law of Multiple Proportions states that:
A. Elements can form more than one compound in different proportions.
B. Mass can neither be created nor destroyed.
C. Atoms cannot be divided further.
D. All atoms of a given element are identical.
A. The Law of Multiple Proportions states that elements can form more than one compound in different proportions.
Question 8: Dalton’s atomic theory failed to explain the behavior of which of the following?
A. Cathode rays
B. Electrically charged substances
C. The periodic table
D. Electromagnetic radiation
B. Dalton’s atomic theory could not explain the behavior of electrically charged substances like glass or ebonite when rubbed with silk or fur.
Question 9: Who discovered that electricity passed through an electrolyte results in chemical reactions at the electrodes?
A. J.J. Thomson
B. Ernest Rutherford
C. Michael Faraday
D. Niels Bohr
C. Michael Faraday showed this phenomenon in 1830.
Question 10: Cathode rays were discovered using which experimental setup?
A. Gold Foil Experiment
B. Cathode Ray Discharge Tube
C. Oil Drop Experiment
D. Rutherford’s Scattering Experiment
B. The Cathode Ray Discharge Tube experiment led to the discovery of cathode rays.
Question 11: Which of the following is NOT a property of cathode rays?
A. They travel in straight lines in the absence of an electric or magnetic field.
B. They consist of negatively charged particles.
C. They originate from the anode and move towards the cathode.
D. They cause fluorescent materials to glow.
C. Cathode rays originate from the cathode and move towards the anode.
Question 12: What conclusion was drawn from the cathode ray experiment regarding the structure of the atom?
A. Atoms are made up of subatomic particles.
B. Atoms are indivisible.
C. Atoms contain positively charged particles.
D. Atoms are electrically neutral.
A. The cathode ray experiment showed that atoms are made up of subatomic particles, specifically electrons.
Question 13: J.J. Thomson discovered the charge to mass ratio of the electron using what type of experiment?
A. Oil Drop Experiment
B. Cathode Ray Tube Experiment
C. Alpha Particle Scattering Experiment
D. X-ray Diffraction
B. Thomson discovered the charge to mass ratio of the electron using the Cathode Ray Tube Experiment.
Question 14: The charge to mass ratio of the electron is measured as:
A. $1.758820 \times 10^{11}$ C kg⁻¹
B. $9.1094 \times 10^{-31}$ C kg⁻¹
C. $1.6726216 \times 10^{-27}$ C kg⁻¹
D. $6.626 \times 10^{-34}$ J s
A. The charge to mass ratio of the electron is $1.758820 \times 10^{11}$ C kg⁻¹.
Question 15: Which factor does NOT influence the deflection of electrons in Thomson’s experiment?
A. The strength of the magnetic field
B. The strength of the electric field
C. The mass of the electron
D. The charge of the positive electrode
D. The charge of the positive electrode does not directly influence the deflection of electrons.
Question 16: Who determined the charge on the electron using the oil drop experiment?
A. J.J. Thomson
B. Ernest Rutherford
C. R.A. Millikan
D. Niels Bohr
C. R.A. Millikan determined the charge on the electron using the oil drop experiment.
Question 17: The charge on the electron was measured to be:
A. $1.758820 \times 10^{11}$ C
B. –$1.602176 \times 10^{-19}$ C
C. $9.1094 \times 10^{-31}$ C
D. $6.022 \times 10^{23}$ C
B. The charge on the electron is –$1.602176 \times 10^{-19}$ C.
Question 18: The mass of the electron was calculated by combining Millikan’s result with Thomson’s charge to mass ratio. What is the mass of the electron?
A. $9.1094 \times 10^{-31}$ kg
B. $1.6726 \times 10^{-27}$ kg
C. 1.0087 u
D. $1.758820 \times 10^{11}$ kg
A. The mass of the electron is $9.1094 \times 10^{-31}$ kg.
Question 19: Protons were first observed in experiments involving what type of rays?
A. Alpha rays
B. Cathode rays
C. Canal rays
D. Gamma rays
C. Protons were first observed in experiments involving canal rays.
Question 20: The mass of a proton compared to that of an electron is approximately:
A. 2000 times greater
B. 1000 times smaller
C. 500 times smaller
D. Equal
A. The mass of a proton is approximately 2000 times greater than that of an electron.
Question 21: Which scientist is credited with the discovery of the neutron?
A. Ernest Rutherford
B. J.J. Thomson
C. James Chadwick
D. R.A. Millikan
C. James Chadwick discovered the neutron in 1932.
Question 22: Neutrons were discovered by bombarding which material with alpha particles?
A. Gold
B. Hydrogen
C. Beryllium
D. Lead
C. Neutrons were discovered by bombarding a thin sheet of beryllium with alpha particles.
Question 23: Which of the following correctly describes the characteristics of protons?
A. They carry a negative charge.
B. They have a mass similar to that of neutrons.
C. They are found outside the nucleus.
D. They are neutrally charged.
B. Protons have a mass similar to that of neutrons.
Question 24: In what year were protons first characterized as positively charged particles?
A. 1897
B. 1906
C. 1919
D. 1932
C. Protons were first characterized as positively charged particles in 1919.
Question 25: Neutrons have which of the following properties?
A. Negative charge and small mass
B. Positive charge and large mass
C. No charge and a mass slightly greater than that of protons
D. Negative charge and a mass equal to electrons
C. Neutrons have no charge and a mass slightly greater than that of protons.
Question 26: Which experiment led to the discovery of positively charged particles (protons)?
A. Oil Drop Experiment
B. Gold Foil Experiment
C. Cathode Ray Tube Experiment
D. Canal Ray Experiment
D. The Canal Ray Experiment led to the discovery of positively charged particles (protons).
Question 27: In Thomson’s Plum Pudding Model, the atom is described as:
A. A positive charge sphere with electrons scattered inside
B. A nucleus surrounded by electrons in specific orbits
C. A nucleus containing protons and neutrons
D. Electrons revolving in elliptical orbits
A. Thomson’s Plum Pudding Model describes the atom as a sphere of positive charge with electrons scattered inside.
Question 28: Which of the following is a limitation of Thomson’s Plum Pudding Model?
A. It could not explain the overall neutrality of the atom.
B. It failed to explain the results of later experiments.
C. It predicted the existence of neutrons incorrectly.
D. It overestimated the number of protons in the nucleus.
B. Thomson’s model failed to explain the results of later experiments, like Rutherford’s scattering experiment.
Question 29: Thomson’s model visualizes the atom as:
A. A dense nucleus with electrons revolving around it
B. A sphere with evenly distributed mass
C. A positively charged pudding with negative electrons embedded
D. A neutral particle with no internal structure
C. Thomson’s model visualizes the atom as a positively charged pudding with negative electrons embedded.
Question 30: Which experiment led to the eventual discrediting of Thomson’s model?
A. Oil Drop Experiment
B. Rutherford’s Gold Foil Experiment
C. Millikan’s Oil Drop Experiment
D. Faraday’s Cathode Ray Discharge Experiment
B. Rutherford’s Gold Foil Experiment led to the eventual discrediting of Thomson’s Plum Pudding Model.
Question 31: Rutherford’s Nuclear Model of the atom was based on which famous experiment?
A. Cathode Ray Tube Experiment
B. Gold Foil Experiment
C. Millikan’s Oil Drop Experiment
D. Photoelectric Effect Experiment
B. Rutherford’s Nuclear Model was based on the Gold Foil Experiment.
Question 32: What was the major observation from Rutherford’s Gold Foil Experiment?
A. Most alpha particles passed through the foil with no deflection.
B. Most alpha particles were deflected at large angles.
C. Alpha particles bounced back directly from the foil.
D. Alpha particles emitted light upon striking the foil.
A. Most alpha particles passed through the foil with no deflection, suggesting that most of the atom is empty space.
Question 33: What did Rutherford conclude about the structure of the atom from his experiment?
A. Atoms consist mainly of empty space.
B. Electrons are embedded within a sphere of positive charge.
C. Protons and electrons are evenly distributed within the atom.
D. Neutrons and protons are the same particles.
A. Rutherford concluded that atoms consist mainly of empty space, with a small, dense nucleus.
Question 34: In Rutherford’s model, the nucleus is described as:
A. Large and positively charged
B. Small and neutrally charged
C. Dense and positively charged
D. Large and negatively charged
C. The nucleus is described as small, dense, and positively charged.
Question 35: Which of the following is NOT a conclusion of Rutherford’s experiment?
A. The atom is mostly empty space.
B. The nucleus contains protons and neutrons.
C. The nucleus is positively charge
D. D. Electrons move around the nucleus in circular orbits.
B. Rutherford’s experiment did not lead to the discovery of neutrons; they were discovered later by Chadwick.
Question 36: Rutherford’s model was unable to explain which of the following?
A. The existence of the atomic nucleus
B. The arrangement of electrons around the nucleus
C. The mass of the proton
D. The existence of neutrons
B. Rutherford’s model was unable to explain the arrangement of electrons around the nucleus.
Question 37: What feature of Rutherford’s model resembles the solar system?
A. The electrons are stationary around the nucleus.
B. The nucleus plays the role of the Sun, and the electrons revolve like planets.
C. The atom is filled with dense matter.
D. Neutrons act like planets revolving around protons.
B. Rutherford’s model resembles the solar system, with the nucleus as the Sun and electrons revolving like planets.
Question 38: The atomic number of an element is defined as the number of:
A. Electrons in an atom
B. Protons in the nucleus
C. Neutrons in the nucleus
D. Nucleons in the nucleus
B. The atomic number is defined as the number of protons in the nucleus of an atom.
Question 39: What does the mass number of an atom represent?
A. The number of protons
B. The number of neutrons
C. The total number of protons and neutrons
D. The total number of electrons
C. The mass number represents the total number of protons and neutrons in the nucleus.
Question 40: Isobars are atoms with:
A. The same number of protons but different numbers of neutrons
B. The same mass number but different atomic numbers
C. The same number of electrons but different mass numbers
D. Identical atomic numbers and mass numbers
B. Isobars are atoms with the same mass number but different atomic numbers.
Question 41: Isotopes of an element differ in the number of:
A. Protons
B. Electrons
C. Neutrons
D. Nucleons
C. Isotopes of an element differ in the number of neutrons.
Question 42: Which theory explains the wave nature of light?
A. Bohr’s Theory
B. Planck’s Quantum Theory
C. Maxwell’s Electromagnetic Theory
D. Rutherford’s Nuclear Theory
C. Maxwell’s Electromagnetic Theory explains the wave nature of light.
Question 43: What is the speed of light in a vacuum?
A. $3.0 \times 10^6$ m/s
B. $3.0 \times 10^8$ m/s
C. $6.022 \times 10^{23}$ m/s
D. $9.11 \times 10^{-31}$ m/s
B. The speed of light in a vacuum is $3.0 \times 10^8$ m/s.
Question 44: The relationship between frequency ($\nu$), wavelength ($\lambda$), and speed of light (c) is given by which equation?
A. E = mc²
B. c = $\nu\lambda$
C. F = ma
D. P = IV
B. The relationship between frequency, wavelength, and the speed of light is given by the equation c = $\nu\lambda$.
