Atoms and subatomic particles Knowledge-Based Practice

Questions

1. 1.

   What is the quark composition of a proton?

   • A) One up quark and two down quarks
   • B) Two up quarks and one down quark
   • C) Three up quarks
   • D) Three down quarks
2. 2.

   Which subatomic particle was discovered by James Chadwick in 1932 through experiments involving the bombardment of beryllium with alpha particles?

   • A) Proton
   • B) Neutron
   • C) Electron
   • D) Neutrino
3. 3.

   How does the magnitude of the electric charge carried by a single proton compare to that carried by a single electron?

   • A) The proton carries a much larger charge magnitude because its mass is roughly 1,836 times greater.
   • B) The electron carries a larger charge magnitude because it is distributed over a much larger volume.
   • C) The proton carries a slightly smaller charge magnitude because nuclear binding reduces its net charge.
   • D) The two particles carry electric charges of identical magnitude despite their vast difference in mass.
4. 4.

   Which experimental observation in Rutherford's gold foil experiment led to the discovery of the dense, positively charged atomic nucleus?

   • A) All alpha particles passed straight through the foil without any change in direction.
   • B) High-energy electrons were ejected from the gold atoms upon collision.
   • C) A very small fraction of alpha particles deflected at angles greater than 90 degrees.
   • D) The gold foil absorbed the majority of the incoming positively charged particles.
5. 5.

   Why do atomic nuclei containing multiple positively charged protons remain stable instead of flying apart due to electrostatic repulsion?

   • A) Gravitational attraction between nucleons overcomes electrostatic repulsion at subatomic distances.
   • B) Surrounding orbital electrons exert an inward electrostatic force that holds the nucleus together.
   • C) The weak nuclear force neutralizes the positive electric charges of adjacent protons in the nucleus.
   • D) The attractive strong nuclear force acting between nucleons overcomes electrostatic repulsion at short distances.
6. 6.

   What determines the net electric charge of an atomic nucleus?

   • A) The difference between the number of protons and electrons
   • B) The total number of nucleons in the nucleus
   • C) The number of protons present in the nucleus
   • D) The number of neutrons present in the nucleus
7. 7.

   What happens to an electron in an atom when it absorbs a photon with energy equal to the difference between two energy levels?

   • A) It falls into the atomic nucleus due to increased electrostatic attraction.
   • B) It splits into constituent subatomic particles that escape the atom.
   • C) It transitions from a lower energy level to a higher energy level.
   • D) It remains in its original energy level while increasing its electric charge.
8. 8.

   Which subatomic particles directly participate in chemical bonding and primarily determine the chemical reactivity of an atom?

   • A) Neutrons residing in the atomic nucleus
   • B) Valence electrons residing in the outermost energy level
   • C) Protons residing in the atomic nucleus
   • D) Core electrons residing in the innermost energy level
9. 9.

   In experiments with cathode ray tubes, the emitted rays were observed to deflect toward positively charged plates and away from negatively charged plates. Which subatomic particle was discovered through these observations?

   • A) Proton
   • B) Neutron
   • C) Positron
   • D) Electron
10. 10.

    Which subatomic particle found within an atom is an elementary particle that is not composed of smaller constituents?

    • A) Electron
    • B) Proton
    • C) Neutron
    • D) Alpha particle
11. 11.

    Which fundamental force is primarily responsible for binding electrons to the atomic nucleus?

    • A) Gravitational force
    • B) Strong nuclear force
    • C) Electromagnetic force
    • D) Weak nuclear force
12. 12.

    A calcium ion has an atomic number of 20 and a net electric charge of +2. How many electrons are present in this ion?

    • A) 18
    • B) 20
    • C) 22
    • D) 2
13. 13.

    An electrically neutral atom has a mass number of 31 and contains 15 electrons. How many neutrons are present in the nucleus of this atom?

    • A) 16
    • B) 15
    • C) 31
    • D) 46
14. 14.

    Which statement correctly describes the distribution of mass and volume within an atom?

    • A) The nucleus contains nearly all of the atom's mass but occupies only a tiny fraction of its total volume.
    • B) The electron cloud accounts for most of the atom's mass as well as most of its total volume.
    • C) The mass and volume of an atom are distributed uniformly throughout its entire spherical structure.
    • D) The nucleus occupies most of the atom's volume, while the electron cloud contains nearly all of its mass.
15. 15.

    Which change causes an electrically neutral atom to become a negatively charged ion (anion)?

    • A) Losing one or more protons from the nucleus
    • B) Gaining one or more neutrons in the nucleus
    • C) Losing one or more electrons from the electron cloud
    • D) Gaining one or more electrons into the electron cloud
16. 16.

    Which statement correctly describes two isotopes of the same chemical element?

    • A) They have different numbers of protons but the same number of neutrons.
    • B) They have identical numbers of protons but different numbers of neutrons.
    • C) They have identical mass numbers but different atomic numbers.
    • D) They have different numbers of electrons when both atoms are electrically neutral.
17. 17.

    What determines the mass number of an atom?

    • A) The sum of the number of protons and neutrons in the nucleus
    • B) The sum of the number of protons and electrons in the atom
    • C) The total number of neutrons subtracted from the number of protons
    • D) The total number of electrons orbiting the nucleus
18. 18.

    Which characteristic uniquely identifies an atom as belonging to a specific chemical element?

    • A) The total number of neutrons in its nucleus
    • B) The total number of electrons surrounding its nucleus
    • C) The number of protons located in its nucleus
    • D) The combined total of its protons and neutrons
19. 19.

    Which statement correctly compares the masses of the three primary subatomic particles in an atom?

    • A) Neutrons and electrons have nearly equal masses, while protons are much lighter.
    • B) Electrons and protons have nearly equal masses, while neutrons are much heavier.
    • C) Protons, neutrons, and electrons all possess approximately identical masses.
    • D) Protons and neutrons have nearly equal masses, while electrons have significantly less mass.
20. 20.

    Which statement correctly describes the location and electrical charge of subatomic particles in an atom?

    • A) Protons have a negative charge and orbit the nucleus, while electrons have a positive charge inside the nucleus.
    • B) Neutrons have a positive charge and are located in the nucleus, while electrons are neutral particles outside the nucleus.
    • C) Protons and electrons are tightly bound inside the nucleus, while electrically neutral neutrons orbit around them.
    • D) Protons are positively charged and located in the nucleus alongside neutral neutrons, while negatively charged electrons surround the nucleus.

Answers and step-by-step solutions appear after you finish the test.