Free Atomic Structure MCQs with Answers
922 Atomic Structure MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Atomic structure covers the discovery of the proton, Planck's quantum theory, hydrogen emission spectra and the evidence for quantized energy levels. You will use quantum numbers to describe orbitals, distinguish s, p, d and f orbital shapes, and write electronic configurations, including the correct order of electron filling.
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922 questions · page 3 of 47
- A. Electron
- B. Proton
- C. Neutron
- D. All have mass
Explanation: A neutron is slightly heavier than a proton, with a mass of about 1.675 x 10^-27 kg compared with about 1.673 x 10^-27 kg for a proton…
Correct answer: Neutron- A. arrangement of electrons in orbitals
- B. position in the periodic table
- C. properties depend upon mass
- D. chemical properties
Explanation: Isotopes are atoms of the same element with the same atomic number but different mass numbers, because they contain different numbers of…
Correct answer: properties depend upon mass- A. Mass
- B. e/m ratio
- C. Isotopes
- D. None of These
Explanation: A mass spectrometer separates ions according to their mass-to-charge ratio, m/z, by combining electric and magnetic fields.
Correct answer: e/m ratio- A. Shell
- B. Orbit
- C. Nucleus
- D. Orbital
Explanation: Nearly all an atom's mass is concentrated in its nucleus because it contains the relatively heavy protons and neutrons, whereas electrons…
Correct answer: Nucleus- A. +ve
- B. -ve
- C. Neutral
- D. None of them
Explanation: A positron is the antimatter counterpart of the electron, so it has the same mass as an electron but a positive charge.
Correct answer: +ve- A. Cathode rays
- B. Canal rays
- C. X-rays
- D. Alpha rays
Explanation: Canal rays, also called positive rays, consist of positively charged ions and were observed by Eugen Goldstein.
Correct answer: Canal rays- A. Proton and neutron
- B. Neutron and electron
- C. Proton
- D. Neutron
Explanation: Every atomic nucleus contains protons, and the number of protons defines the element’s atomic number.
Correct answer: Proton- A. 10 disintegration per second
- B. 1.5 disintegration per second
- C. 0.01 disintegration per second
- D. 1 disintegration per second
Explanation: The becquerel is the SI unit of activity, defined as one nuclear disintegration per second: 1 Bq = 1 disintegration s^-1.
Correct answer: 1 disintegration per second- A. Beta particle
- B. Gamma particle
- C. Alpha particle
- D. Negative particle
Explanation: An alpha particle is a helium-4 nucleus containing two protons and two neutrons, so its net charge is +2e.
Correct answer: Alpha particle- A. Radio elements
- B. Active elements
- C. Radioactive elements
- D. Nuclear elements
Explanation: Elements that spontaneously emit alpha, beta or gamma radiation from unstable nuclei are called radioactive elements.
Correct answer: Radioactive elements- A. e
- B. 2e
- C. 3e
- D. 4e
Explanation: An alpha particle is a helium nucleus with two protons, and each proton contributes a charge of +e, giving a total charge of +2e.
Correct answer: 2e- A. Gold foils
- B. Barium sulphate
- C. Zinc sulphide screen
- D. Thin Aluminium sheet
Explanation: Alpha particles produce flashes of light when they strike a zinc sulphide screen, allowing their paths or impacts to be detected.
Correct answer: Zinc sulphide screen- A. Fast neutrons
- B. Slow neutrons
- C. Moderate neutrons
- D. All are possible
Explanation: Neutron speed is related to its kinetic energy, and a neutron with energy in the MeV range is classified as a fast neutron.
Correct answer: Fast neutrons- A. Attractive forces
- B. Repulsive force
- C. Electrons
- D. Neutrons
Explanation: In the classical model of an atom, the outward centrifugal effect associated with an electron’s circular motion is balanced by the inward…
Correct answer: Attractive forces- A. Electron
- B. Positron
- C. Neutron
- D. None of above has such capability
Explanation: Fast neutrons can knock protons out of hydrogen-rich paraffin by elastic collisions, because paraffin contains many hydrogen nuclei and a…
Correct answer: Neutron- A. Gamma-rays
- B. Alpha-rays
- C. Beta-rays
- D. X-rays
Explanation: Rutherford used alpha particles, which are positively charged helium nuclei, in the gold-foil experiment that revealed the small, dense…
Correct answer: Alpha-rays- A. J.J Thomson
- B. Millikan
- C. Rutherford
- D. Perrin
Explanation: Millikan measured the magnitude of the electron’s charge using the oil-drop experiment by balancing electrical force against gravitational…
Correct answer: Millikan- A. Neutrino
- B. Electron
- C. Both A & B
- D. Meson
Explanation: In beta-minus decay, a free neutron changes into a proton while emitting an electron and an antineutrino: n → p + e⁻ + antineutrino.
Correct answer: Both A & B- A. Alpha emission
- B. Beta emission
- C. Both A & B
- D. Radioactivity
Explanation: In beta-minus emission, a neutron changes into a proton and an electron, so the atomic number increases by 1 while the mass number remains…
Correct answer: Beta emission60. The number of fundamental particles in an atom of the lightest isotope carbon are_______________?
- A. 6
- B. 12
- C. 18
- D. 20
Explanation: The lightest isotope of carbon is carbon-12, containing 6 protons, 6 neutrons and 6 electrons.
Correct answer: 18