Atoms and subatomic particles Transitional Reasoning Practice

Questions

1. 1.

   In a vacuum test chamber, an isolated proton and an isolated electron are placed separately into identical uniform electric fields. A researcher analyzes the instantaneous electrostatic force acting on each particle and their resulting accelerations at the moment of release. Based on the fundamental charges and masses of subatomic particles, which statement correctly compares the force and acceleration experienced by the electron to those experienced by the proton?

   • A) The electrostatic force on the proton is substantially greater because of its larger mass, so the two particles achieve equal accelerations.
   • B) The electrostatic forces on both particles are equal in magnitude, but the electron experiences a far greater acceleration because of its much smaller mass.
   • C) The electrostatic force on the electron is substantially greater because of its negative charge, causing it to undergo a far greater acceleration.
   • D) Both the electrostatic forces and the resulting accelerations have identical magnitudes because both particles carry the same magnitude of electric charge.
2. 2.

   A physics student compares the subatomic structures of two microscopic species: a neutral protium atom ($^1\text{H}$) and a deuterium ion ($^2\text{H}^+$). Both species are forms of hydrogen with an atomic number of 1, where protium has a mass number of 1 and deuterium has a mass number of 2. Based on the fundamental properties and locations of subatomic particles, which conclusion correctly compares these two species?

   • A) Both species possess identical numbers of neutrons, but the deuterium ion has fewer electrons.
   • B) The deuterium ion contains a greater total number of fundamental subatomic particles than the neutral protium atom because of its higher mass number.
   • C) The neutral protium atom has a greater net electric charge than the deuterium ion because it contains both protons and electrons.
   • D) Both species contain the exact same total number of fundamental subatomic particles, but all subatomic particles in the deuterium ion reside within its nucleus.
3. 3.

   An isolated neutral atom undergoes a specific transformation that changes its subatomic composition. Following this transformation, measurements reveal that the atom's chemical identity remains completely unchanged, its mass number has decreased by 1, and its net electric charge is now +1. Based on the distinct roles and properties of subatomic particles, which change in subatomic composition took place?

   • A) The atom gained one proton in its nucleus and lost two neutrons.
   • B) The atom lost one proton from its nucleus and gained one electron in its electron cloud.
   • C) The atom lost one neutron from its nucleus and one electron from its electron cloud.
   • D) The atom lost one neutron from its nucleus and gained one proton.
4. 4.

   In a series of electrical discharge experiments, researchers test cathode-ray tubes equipped with electrodes made of different metals (copper, iron, and silver) and filled with various low-pressure gases. In every trial, the emitted rays deflect toward a positively charged external plate and exhibit the exact same mass-to-charge ratio. Based on these experimental findings, what conclusion must be drawn about the nature of subatomic particles?

   • A) Negatively charged subatomic particles (electrons) are identical, universal constituents present in the atoms of all elements.
   • B) The positive charge of an atom is concentrated within a tiny nucleus that deflects external electric fields.
   • C) Protons and neutrons can be readily liberated from atomic nuclei by applying an electric potential difference.
   • D) Different chemical elements contain subatomic particles that possess unique, element-specific magnitudes of electric charge.
5. 5.

   A laboratory team designs an experiment to alter a neutral beryllium atom, which contains 4 protons, 5 neutrons, and 4 electrons, so that the resulting particle is attracted toward a negatively charged plate. The procedure must also strictly preserve the chemical identity of beryllium and leave its mass number unaffected. Based on the roles and characteristics of subatomic particles, which modification achieves this result?

   • A) Removing one neutron from the nucleus, because eliminating an uncharged particle unbalances the nuclear charge without altering the atomic number.
   • B) Removing one electron from the electron cloud, because the proton count remains 4 to preserve chemical identity while the loss of negative charge yields a net positive ion.
   • C) Adding one proton to the nucleus, because introducing a positive charge creates the required electrostatic attraction while the unchanged electron count preserves identity.
   • D) Adding one electron to the electron cloud, because an additional valence charge allows the atom to polarize positively toward the negative plate.
6. 6.

   A laboratory analyzes two different monoatomic ions, Ion X and Ion Y, which both possess exactly 18 electrons in their electron clouds. Ion X carries a net electric charge of +2, whereas Ion Y carries a net electric charge of -1. Based on the fundamental charges and roles of subatomic particles, which statement correctly compares the nuclear compositions and identities of these two ions?

   • A) Ion X and Ion Y belong to the same chemical element because possessing an identical number of electrons dictates identical nuclear charge and atomic identity.
   • B) Ion X contains 16 protons and Ion Y contains 19 protons, so Ion Y has a greater nuclear charge and a higher atomic number than Ion X.
   • C) Ion X contains 18 protons and 20 electrons, whereas Ion Y contains 18 protons and 17 electrons, showing that net charge depends entirely on shifting nuclear protons.
   • D) Ion X contains 20 protons in its nucleus while Ion Y contains 17 protons, meaning Ion X has a greater nuclear charge and a higher atomic number than Ion Y.
7. 7.

   A mass spectrometry analysis of a naturally occurring element identifies two stable isotopes: Isotope-1 with a mass number of 20 and a relative abundance of 90%, and Isotope-2 with a mass number of 22 and a relative abundance of 10%. Physical measurements confirm that both isotopes possess a nuclear charge of $+10\text{ e}$. Based on the subatomic structure and relative abundances of these isotopes, which conclusion correctly describes this element?

   • A) Both isotopes contain 10 protons but differ by 2 neutrons, yielding an atomic number of 10 and a weighted average atomic mass of 20.2 u.
   • B) Both isotopes contain 10 protons but differ by 2 neutrons, yielding an atomic number of 10 and an unweighted average atomic mass of 21.0 u.
   • C) Isotope-2 contains 2 more protons than Isotope-1, yielding different atomic numbers and a weighted average atomic mass of 20.2 u.
   • D) Both isotopes contain 10 neutrons but differ by 2 electrons, yielding an atomic number of 10 and an average atomic mass of 22.0 u.
8. 8.

   A research team analyzes four atomic nuclei—labeled W, X, Y, and Z—to evaluate how subatomic particle counts determine nuclear properties: Nucleus W contains 6 protons and 6 neutrons; Nucleus X contains 6 protons and 8 neutrons; Nucleus Y contains 7 protons and 7 neutrons; and Nucleus Z contains 8 protons and 6 neutrons. Based on the fundamental roles and properties of these subatomic particles, which conclusion correctly compares the nuclear charges and mass numbers of these nuclei?

   • A) Nuclei W and X have different nuclear charges because they contain different numbers of neutrons.
   • B) Nuclei Y and Z possess the same nuclear charge because their mass numbers are equal.
   • C) Nuclei X, Y, and Z have identical mass numbers but exhibit three different nuclear charges.
   • D) Nucleus W has a greater nuclear charge than Nucleus X because having fewer neutrons concentrates the positive charge.
9. 9.

   An analytical team analyzes an uncharged atom of an unknown element. Mass and spectroscopic data reveal that the nucleus has a mass number of 32 and contains 4 more neutrons than protons. Based on the structure and properties of subatomic particles, how many electrons surround this nucleus, and what is the total number of fundamental subatomic particles in the atom?

   • A) 18 electrons, with a total of 50 subatomic particles
   • B) 16 electrons, with a total of 48 subatomic particles
   • C) 14 electrons, with a total of 46 subatomic particles
   • D) 14 electrons, with a total of 32 subatomic particles
10. 10.

    In an investigation of atomic structure, a researcher analyzes the three fundamental subatomic particles—designated X, Y, and Z—present in a neutral atom. Particle X is located in the region outside the nucleus, while particles Y and Z reside together inside the nucleus. Particle Y has an electric charge equal in magnitude but opposite in sign to Particle X, whereas Particle Z has no electric charge. If this neutral atom loses two particles of type X, which statement correctly describes the resulting species?

    • A) Its atomic number decreases by 2, and its net electric charge becomes $-2$.
    • B) Its mass number decreases by 2, while its net electric charge remains neutral.
    • C) Its net electric charge becomes $+2$, while its atomic number and mass number remain unchanged.
    • D) Its net electric charge becomes $+2$, but its mass number decreases by 2.
11. 11.

    A laboratory analysis determines the subatomic compositions of three isolated microscopic species: Particle K consists of 9 protons, 10 neutrons, and 10 electrons; Particle L consists of 9 protons, 10 neutrons, and 9 electrons; and Particle M consists of 10 protons, 10 neutrons, and 10 electrons. Based on the fundamental roles and properties of subatomic particles, which conclusion correctly compares these species?

    • A) Particles K and L belong to the same chemical element because they possess the same nuclear charge, but Particle K carries a net negative charge while Particle L is electrically neutral.
    • B) Particles K and M belong to the same chemical element because they have identical numbers of electrons, while Particle L represents a different element due to its smaller electron count.
    • C) Particles K and L belong to different chemical elements because their electron counts differ, giving Particle K a net positive charge and Particle L a neutral state.
    • D) Particles L and M belong to the same chemical element because they have identical net electrical charges, while Particle K represents an entirely different element.
12. 12.

    An analytical laboratory examines an isolated monoatomic ion with a net electric charge of +3. Physical measurements reveal that this ion contains 10 electrons in its electron cloud and 14 neutrons in its nucleus. Based on the fundamental relationships among subatomic particles, what are the atomic number and the mass number of this ion?

    • A) Atomic number = 10, Mass number = 24
    • B) Atomic number = 7, Mass number = 21
    • C) Atomic number = 13, Mass number = 27
    • D) Atomic number = 13, Mass number = 37
13. 13.

    In a materials laboratory, an investigation demonstrates that when two neutral insulating objects are rubbed together, negative electric charge is transferred between them, while neither object changes its chemical identity or atomic number. A researcher evaluates which subatomic constituent is responsible for this transfer and why other subatomic particles remain unaffected. Based on the organization and characteristics of subatomic particles within atoms, which conclusion accurately explains this outcome?

    • A) Electrons reside in outer regions around the nucleus and are easily transferred between atoms, whereas protons and neutrons are tightly confined inside the massive nucleus.
    • B) Protons carry negative charges that easily detach from outer atomic shells, whereas neutrons and electrons form a rigid core that cannot lose particles.
    • C) Neutrons are the lightest subatomic particles and readily migrate across surfaces, whereas protons and electrons are permanently bound within the nucleus.
    • D) Both protons and electrons transfer in equal quantities across surfaces, but the positive charge of transferred protons is instantly neutralized by nuclear forces.
14. 14.

    A student analyzes the fundamental electrostatic forces operating among the subatomic particles in a neutral helium atom, which contains two protons and two neutrons in its nucleus surrounded by two electrons. Based on the electric charges of these subatomic particles, which statement correctly describes the electrostatic interactions occurring within the atom?

    • A) Protons exert repulsive electrostatic forces on one another, whereas neutrons neither exert nor experience electrostatic forces with the other particles.
    • B) Protons and electrons repel one another because they occupy different regions of the atom, whereas neutrons attract protons electrostatically.
    • C) Neutrons exert attractive electrostatic forces on protons to hold the nucleus together, whereas electrons attract one another in the surrounding cloud.
    • D) Electrons attract one another within the electron cloud, whereas neutrons repel each other inside the nucleus due to their neutral state.
15. 15.

    An experimental detector records data for two subatomic constituents extracted from a neutral atom: Particle X has an electric charge of $+1\text{ e}$ and a relative mass of approximately $1\text{ u}$, while Particle Y has an electric charge of $-1\text{ e}$ and a relative mass of approximately $1/1836\text{ u}$. Based on their fundamental characteristics and roles in atomic structure, which conclusion accurately evaluates these two particles?

    • A) Particle X is an electron located outside the nucleus that determines the atom's overall volume, while Particle Y is a proton located in the nucleus that contributes almost all the atom's mass.
    • B) Particle X is a proton residing in the nucleus that can be freely exchanged during chemical reactions, while Particle Y is a neutron whose count determines the atom's net electrical charge.
    • C) Particle X is a proton located in the nucleus that significantly contributes to the atom's mass, while Particle Y is an electron located outside the nucleus whose equal but opposite charge establishes electrical neutrality.
    • D) Particle X is a neutron located inside the nucleus that stabilizes atomic structure, while Particle Y is an electron whose mass accounts for the vast majority of the atom's inertia.
16. 16.

    A materials scientist analyzes two distinct neutral atomic species, Sample X and Sample Y. Laboratory measurements confirm that both samples have an identical mass number of 40, but Sample X contains 18 protons while Sample Y contains 20 protons. Based on the roles and properties of subatomic particles, which statement correctly explains why Sample X and Sample Y exhibit completely different chemical behaviors?

    • A) Sample X and Sample Y possess different numbers of neutrons, which directly govern the chemical bonding behavior of atoms.
    • B) The number of protons determines the elemental identity and dictates the electron count in a neutral atom, which governs chemical properties.
    • C) The equal mass numbers ensure that both samples have identical electron arrangements, making nuclear stability the only distinguishing factor.
    • D) Sample Y contains fewer electrons than protons in its neutral state, generating a net electrostatic charge that alters its reactivity.
17. 17.

    In a particle demonstration, a collimated horizontal beam containing isolated protons, neutrons, and electrons enters the gap between two parallel charged plates, where the top plate is positively charged and the bottom plate is negatively charged. Sensors positioned at the opposite end of the chamber record the path followed by each type of particle. Based on the fundamental charges of subatomic particles, which observation correctly describes the deflection of these particles?

    • A) Protons curve upward toward the top plate, whereas electrons curve downward toward the bottom plate because positive charges move toward regions of higher potential.
    • B) Neutrons curve downward toward the bottom plate alongside protons because both particles originate from the atomic nucleus.
    • C) Electrons curve upward toward the top plate, protons curve downward toward the bottom plate, and neutrons travel straight without deflection.
    • D) All three particle types travel straight through the chamber without curving because subatomic particles only experience electrostatic forces when bound inside an atom.
18. 18.

    A research team investigates the internal structure of an uncharged atom and measures the mass and volume contributions of its constituent regions. Their data show that over 99.9% of the atom's total mass is concentrated within a tiny central core with a positive charge, while the surrounding outer region determines the atom's overall size. Based on the properties and locations of subatomic particles, which statement correctly explains this observation?

    • A) Neutrons and electrons form a dense positive core at the center, whereas heavier protons orbit the outer boundary of the atom.
    • B) Protons, neutrons, and electrons are distributed uniformly across the entire atomic volume, resulting in an even mass density throughout the atom.
    • C) Protons and neutrons, which carry almost all of the atom's mass, are tightly confined to the tiny central nucleus, whereas lightweight electrons occupy the expansive outer space.
    • D) Protons and electrons have nearly equal masses and reside together in the nucleus, whereas neutral neutrons occupy the vast surrounding space to provide stability.
19. 19.

    A laboratory technician analyzes an isolated particle composed of 8 protons, 8 neutrons, and 10 electrons. To classify the particle, the technician compares it with a neutral oxygen atom containing 8 protons, 8 neutrons, and 8 electrons. Based on the charges and roles of subatomic particles, which conclusion accurately describes this particle?

    • A) It represents a different chemical element because the total number of charged particles has changed from 16 to 18.
    • B) It carries a net positive charge of +2 because the number of electrons exceeds the number of neutrons in the nucleus.
    • C) Its mass number increases by 2 because the two additional electrons contribute significantly to the total nuclear mass.
    • D) It carries a net charge of -2 and retains the elemental identity of oxygen because the number of protons is unchanged.
20. 20.

    A student investigates a neutral atom composed of 6 protons, 6 neutrons, and 6 electrons. The student considers a modification where 1 neutron is added to the nucleus while the counts of all other subatomic particles remain unchanged. Based on the properties of subatomic particles, which statement correctly describes the result of this modification?

    • A) The atom becomes a positively charged ion of a new element with an atomic number of 7.
    • B) The atom remains the same chemical element with no net electrical charge, but its total mass increases.
    • C) The atom becomes a negatively charged isotope of the original element because the nuclear mass increases.
    • D) The atom changes into a different chemical element while remaining electrically neutral.

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