Class 11 – Structure of Atom (35 MCQs)
Discovery of Electron, Proton, Neutron (1–5)
- Who discovered the electron?
a) Rutherford
b) Thomson
c) Bohr
d) Chadwick - The mass of an electron is approximately:
a) 1 u
b) 9.11 × 10⁻³¹ kg
c) 1.67 × 10⁻²⁷ kg
d) 0.5 u - The neutron was discovered by:
a) Rutherford
b) Chadwick
c) Thomson
d) Bohr - Proton has a:
a) Negative charge
b) Positive charge
c) Neutral charge
d) Variable charge - Cathode rays are:
a) Streams of protons
b) Streams of electrons
c) Streams of neutrons
d) Streams of ions
Atomic Models (6–12)
- Thomson’s model of the atom is also called:
a) Planetary model
b) Nuclear model
c) Plum pudding model
d) Bohr model - Rutherford’s gold foil experiment showed that:
a) Atom is indivisible
b) Atom has a dense nucleus
c) Atom has electrons in shells
d) Electrons are protons - Bohr’s model explained:
a) Alpha scattering
b) Hydrogen emission spectrum
c) Electron discovery
d) Neutron mass - Which of the following is NOT true for Rutherford’s model?
a) Atom has a central nucleus
b) Most of the atom is empty space
c) Electrons revolve in fixed orbits
d) Nucleus contains protons - According to Bohr, the angular momentum of an electron is:
a) nh/2π
b) h/n
c) 2πnh
d) √n h - Bohr’s model is limited because it:
a) Explains only hydrogen-like atoms
b) Predicts alpha scattering
c) Explains radioactivity
d) Does not have orbitals - The first atomic model to introduce the concept of a nucleus was:
a) Dalton
b) Thomson
c) Rutherford
d) Bohr
Quantum Numbers & Electronic Configuration (13–20)
- Principal quantum number (n) indicates:
a) Electron spin
b) Energy level
c) Orbital shape
d) Orbital orientation - Angular momentum quantum number (l) defines:
a) Energy of electron
b) Spin of electron
c) Shape of orbital
d) Charge of electron - Magnetic quantum number (mₗ) indicates:
a) Number of electrons
b) Orientation of orbital
c) Spin of electron
d) Principal energy level - Spin quantum number (mₛ) can have values:
a) 0, ±1
b) ±½
c) ±1, ±2
d) Only +1 - The number of orbitals in a p-subshell is:
a) 1
b) 2
c) 3
d) 5 - The maximum number of electrons in a shell is given by:
a) n²
b) 2n²
c) 2n
d) n/2 - The electronic configuration of oxygen (Z = 8) is:
a) 1s²2s²2p⁴
b) 1s²2s²2p⁶
c) 1s²2s²2p²
d) 1s²2p⁶ - Pauli’s exclusion principle states that:
a) No two electrons in an atom can have same set of quantum numbers
b) Electrons occupy lowest energy orbitals first
c) Orbitals of same energy are singly occupied first
d) Electrons move in fixed orbits
Dual Nature of Matter & Heisenberg Uncertainty (21–25)
- De Broglie proposed that electrons have:
a) Only particle nature
b) Only wave nature
c) Both particle and wave nature
d) No mass - The wavelength of a particle is given by:
a) λ = mv
b) λ = h/p
c) λ = E/h
d) λ = h²/p - Heisenberg uncertainty principle states:
a) Energy and mass cannot be simultaneously measured
b) Position and momentum cannot be simultaneously known accurately
c) Only velocity is uncertain
d) Electrons have fixed paths - According to quantum mechanics, electrons do NOT move in:
a) Orbits
b) Orbitals
c) Shells
d) Energy levels - The dual nature of matter is confirmed by:
a) Rutherford experiment
b) Davisson-Germer experiment
c) Bohr model
d) Thomson experiment
Hydrogen Atom Spectrum & Bohr’s Postulates (26–31)
- The series of hydrogen spectrum in visible region is called:
a) Lyman
b) Balmer
c) Paschen
d) Brackett - Bohr’s second postulate states that:
a) Electron moves in circular orbits
b) Angular momentum is quantized
c) Energy of electron is continuous
d) Nucleus is positively charged - The energy of an electron in nth orbit of hydrogen atom is:
a) E = –13.6/n² eV
b) E = –13.6 n² eV
c) E = –1/n eV
d) E = 0 - The emission of light occurs when:
a) Electron moves to higher orbit
b) Electron moves to lower orbit
c) Electron becomes stationary
d) Proton moves - The Rydberg constant (R) is related to:
a) Energy levels of hydrogen
b) Atomic mass
c) Electron spin
d) Neutron mass - The longest wavelength in hydrogen spectrum belongs to:
a) Lyman series
b) Balmer series
c) Paschen series
d) Brackett series
Radioactivity Basics & Isotopes/Isobars/Isotones (32–35)
- Atoms of the same element with different number of neutrons are called:
a) Isotopes
b) Isobars
c) Isotones
d) Allotropes - Atoms of different elements with same mass number are called:
a) Isotopes
b) Isobars
c) Isotones
d) Allotropes - Atoms of different elements with same number of neutrons are called:
a) Isotopes
b) Isobars
c) Isotones
d) Allotropes - Radioactive decay involves:
a) Gain of electrons
b) Loss of nucleons or emission of radiation
c) Change in protons only
d) Movement of electrons to higher orbit
Answer Key – Class 11 Chemistry: Structure of Atom (35 MCQs)
Discovery of Electron, Proton, Neutron (1–5)
- b) Thomson – Discovered electron using cathode ray tube.
- b) 9.11 × 10⁻³¹ kg – Standard mass of an electron.
- b) Chadwick – Discovered neutron in 1932.
- b) Positive charge – Proton has +1 charge.
- b) Streams of electrons – Cathode rays are electrons.
Atomic Models (6–12)
- c) Plum pudding model – Thomson’s atomic model.
- b) Atom has a dense nucleus – Rutherford’s gold foil experiment showed nucleus.
- b) Hydrogen emission spectrum – Bohr explained H atom spectra.
- c) Electrons revolve in fixed orbits – This was added by Bohr, not Rutherford.
- a) nh/2π – Bohr’s angular momentum quantization.
- a) Explains only hydrogen-like atoms – Limitation of Bohr model.
- c) Rutherford – First to introduce the nucleus.
Quantum Numbers & Electronic Configuration (13–20)
- b) Energy level – Principal quantum number defines shell energy.
- c) Shape of orbital – Angular momentum quantum number defines orbital shape.
- b) Orientation of orbital – Magnetic quantum number defines orientation.
- b) ±½ – Spin quantum number can be +½ or –½.
- c) 3 – p-subshell has 3 orbitals.
- b) 2n² – Maximum electrons in a shell.
- a) 1s²2s²2p⁴ – Oxygen has 8 electrons.
- a) No two electrons in an atom can have same set of quantum numbers – Pauli’s principle.
Dual Nature of Matter & Heisenberg Uncertainty (21–25)
- c) Both particle and wave nature – de Broglie hypothesis.
- b) λ = h/p – de Broglie wavelength formula.
- b) Position and momentum cannot be simultaneously known accurately – Heisenberg uncertainty principle.
- a) Orbits – Quantum mechanics replaced fixed orbits with orbitals.
- b) Davisson-Germer experiment – Confirmed wave nature of electrons.
Hydrogen Atom Spectrum & Bohr’s Postulates (26–31)
- b) Balmer – Visible series of H spectrum.
- b) Angular momentum is quantized – Bohr’s 2nd postulate.
- a) E = –13.6/n² eV – Energy of electron in nth orbit.
- b) Electron moves to lower orbit – Emission occurs when electron falls to lower energy.
- a) Energy levels of hydrogen – Rydberg constant used in hydrogen spectra.
- b) Balmer series – Longest wavelength in visible region.
Radioactivity Basics & Isotopes/Isobars/Isotones (32–35)
- a) Isotopes – Same Z, different N.
- b) Isobars – Different Z, same mass number.
- c) Isotones – Different Z, same N.
- b) Loss of nucleons or emission of radiation – Radioactive decay involves emission of α, β, γ or nucleons.
Disclaimer:
All MCQs on this page are created for educational purposes only. They are intended for practice and NEET/Class 11 Chemistry preparation and do not guarantee any specific exam results.