Atoms and subatomic particles Knowledge-Based Download PDF

Questions

1. 1.

   According to the Bohr model of the atom, what is the maximum number of electrons that can occupy the second principal energy level ($n = 2$)?

   • A) 8
   • B) 2
   • C) 6
   • D) 18
2. 2.

   An atom of potassium is represented by the nuclide symbol $^{39}_{19}\text{K}$. How many neutrons are contained in the nucleus of this atom?

   • A) 19
   • B) 39
   • C) 58
   • D) 20
3. 3.

   Cathode rays generated in an evacuated discharge tube consist of a stream of which subatomic particles?

   • A) Electrons
   • B) Protons
   • C) Neutrons
   • D) Alpha particles
4. 4.

   Which combination of up ($u$) and down ($d$) quarks forms a proton?

   • A) One up quark and two down quarks ($udd$)
   • B) Three up quarks ($uuu$)
   • C) Two up quarks and one down quark ($uud$)
   • D) One up quark and one down antiquark ($u\bar{d}$)
5. 5.

   In Rutherford's alpha-particle scattering experiment, which key observation provided direct evidence that an atom's positive charge and most of its mass are concentrated in a tiny central nucleus?

   • A) Nearly all alpha particles were absorbed directly within the gold foil.
   • B) A very small fraction of alpha particles were deflected through large angles, with some rebounding backward.
   • C) Alpha particles were uniformly scattered at identical small angles in all directions.
   • D) The gold foil completely neutralized the positive charge of every passing alpha particle.
6. 6.

   Which subatomic particle found within an atom is classified as an elementary particle because it is not composed of quarks or other smaller components?

   • A) Proton
   • B) Neutron
   • C) Alpha particle
   • D) Electron
7. 7.

   When a beam containing different subatomic particles enters a uniform electric field perpendicular to its velocity, which particle is deflected toward the positively charged plate with the largest acceleration?

   • A) Neutron
   • B) Proton
   • C) Electron
   • D) Alpha particle
8. 8.

   An atomic particle contains 15 protons, 16 neutrons, and 18 electrons. What is the net electric charge of this particle?

   • A) +3
   • B) +1
   • C) -1
   • D) -3
9. 9.

   Which subatomic particles are shared, gained, or lost when atoms interact to form chemical bonds?

   • A) Electrons
   • B) Protons
   • C) Neutrons
   • D) Quarks
10. 10.

    Which term collectively refers to the protons and neutrons located within an atomic nucleus?

    • A) Nucleons
    • B) Leptons
    • C) Quarks
    • D) Isotopes
11. 11.

    Which fundamental force is primarily responsible for overcoming the electrostatic repulsion between protons to hold an atomic nucleus together?

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

    Which type of interaction is primarily responsible for binding electrons to the nucleus in an atom?

    • A) Gravitational attraction between nucleons and electrons
    • B) Strong nuclear force acting across the electron shells
    • C) Electrostatic attraction between opposite electric charges
    • D) Magnetic attraction between aligned subatomic spins
13. 13.

    Which statement accurately compares an electron to a proton regarding their electric charge and mass?

    • A) An electron carries a smaller magnitude of charge than a proton and has roughly the same mass.
    • B) An electron carries an electric charge of equal magnitude but opposite sign, and has substantially less mass than a proton.
    • C) An electron carries an electric charge of the same sign as a proton, but possesses significantly greater mass.
    • D) An electron carries twice the charge magnitude of a proton and has identical mass.
14. 14.

    When an electrically neutral atom is converted into a positively charged ion (cation), which subatomic change takes place?

    • A) It gains one or more protons in its nucleus.
    • B) It loses one or more electrons from its electron cloud.
    • C) It loses one or more neutrons from its nucleus.
    • D) It gains one or more electrons in its electron cloud.
15. 15.

    Which subatomic feature distinguishes two isotopes of the same chemical element from each other?

    • A) A different number of neutrons in the nucleus
    • B) A different number of protons in the nucleus
    • C) A different number of electrons in their neutral states
    • D) A different net electric charge carried by each proton
16. 16.

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

    • A) The nucleus contains a negligible portion of the atom's mass and occupies most of its volume.
    • B) The nucleus contains almost all of the atom's mass while occupying a minute fraction of its volume.
    • C) The nucleus contains roughly half of the atom's mass and occupies approximately half of its volume.
    • D) The nucleus contains almost all of the atom's mass and occupies the vast majority of its volume.
17. 17.

    The mass number of an atom is defined as the total number of which subatomic particles residing in its nucleus?

    • A) Electrons and protons
    • B) Electrons and neutrons
    • C) Protons and neutrons
    • D) Protons, neutrons, and electrons
18. 18.

    In an electrically neutral atom, which relationship between subatomic particles must always hold true?

    • A) The number of protons must equal the number of neutrons.
    • B) The number of neutrons must equal the number of electrons.
    • C) The number of protons must equal the number of electrons.
    • D) The total number of nucleons must equal the number of electrons.
19. 19.

    Which subatomic particle determines the atomic number and uniquely defines the chemical identity of an element?

    • A) Neutron
    • B) Electron
    • C) Proton
    • D) Quark
20. 20.

    Which statement correctly describes the electric charge, relative mass, and location of a neutron in an atom?

    • A) It carries a positive elementary charge, has a mass comparable to a proton, and is located in the nucleus.
    • B) It carries a negative elementary charge, has negligible mass compared to a proton, and surrounds the nucleus.
    • C) It has no net electric charge, has approximately the same mass as a proton, and resides inside the nucleus.
    • D) It has no net electric charge, has negligible mass compared to an electron, and orbits the nucleus.