Physics Ch7 Modern Physics HW set Review
In an experiment, white light is passed through a cloud of atomic hydrogen, and the spectrum is analyzed by passing the light through a diffraction grating. Some wavelengths of light are observed to be missing. One of the missing wavelengths is 434nm. Which of the following gives the approximate energy of the photon responsible for the missing wavelength and indicates whether that energy was sufficient to ionize the hydrogen atom from its ground state? A 2.86eV, which is insufficient to ionize the atom B 2.86eV, which is sufficient to ionize the atom C 4.58×10^−25MeV, which is insufficient to ionize the atom D 2.86MeV, which is sufficient to ionize the atom
A) 2.86eV, which is insufficient to ionize the atom
Np93237→Tl81205+___α+___β− In a nuclear decay chain, a neptunium nucleus eventually becomes a thallium nucleus via a series of alpha and beta minus decays. The net reaction is shown. Which of the following is true of the number of alpha and beta particles produced? A) More alpha particles than beta particles are produced. B) More beta particles than alpha particles are produced. C) An equal number of alpha and beta particles are produced. D) There is no way to determine whether more alpha or beta particles are produced without knowing the individual steps in the process.
A) More alpha particles than beta particles are produced.
Electrons moving at 5000m/s are aimed at single slits of various sizes. In each case, a screen with a width of 1.0m is placed 1.0m from the slit. For which of the following slit widths would a diffraction pattern containing more than five maxima be observed on the screen? A 3×10−9m3×10−9m B 3×10−8m3×10−8m C 3×10−7m3×10−7m D 3×10−6m3×10−6m
D m*wavelength=dsin(theta)
Ra88226→Rn86222+He24 An unstable isotope of radium, with atomic mass 226.025410u, decays into radon of atomic mass 222.017578u and helium of atomic mass 4.002603u, as shown in the reaction. The total energy released during the decay of 100g of radium is most nearly A 1.28×1024MeV B 9.93×1026MeV C 5.50×1028MeV D 5.60×1028MeV
A) 1.28×1024MeV
Sg106263→Rf104259+He24 Consider the decay of Seaborgium-263 (mass=263.118322 u) that forms Rutherfordium-259 (mass=259.105637 u) and an alpha particle (a helium nucleus, mass=4.001506u), as shown in the reaction. How much energy is released in the reaction? A 10.41MeV B 3725.40MeV C 237,501.95MeV D 241,237.76MeV
A) 10.41MeV
The energy levels of the Bohr model for the atom can be expressed mathematically as En=−13.6Z2n2eV, where Z is the atomic number, and n is the quantum number. This model is reasonably accurate for hydrogen and for singly ionized helium. The photon associated with the transition of an electron from the ground state to the first excited state in singly ionized helium has a different wavelength than that associated with a similar transition in hydrogen. Which of the following correctly describes the wavelengths of these two photons in terms of the energy level diagrams for hydrogen and helium? A The photon absorbed by hydrogen has a longer wavelength than that absorbed by helium, because the energy levels in the diagram for hydrogen are more closely spaced than in the diagram for helium. B The photon absorbed by hydrogen has a shorter wavelength than that absorbed by helium, because the energy levels in the diagram for hydrogen are more closely spaced than in the diagram for helium. C The photon absorbed by hydrogen has a longer wavelength than that absorbed by helium, because the energy levels in the diagram for hydrogen are spaced farther apart than in the diagram for helium. D The photon absorbed by hydrogen has a shorter wavelength than that absorbed by helium, because the energy levels in the diagram for hydrogen are spaced farther apart than in the diagram for helium.
A) The photon absorbed by hydrogen has a longer wavelength than that absorbed by helium, because the energy levels in the diagram for hydrogen are more closely spaced than in the diagram for helium.
Which of the following phenomena can be explained by the wave model of light? Select two answers. A Light with a minimum frequency can eject electrons from the surface of a metal. B Atoms can absorb light of a specific frequency. C Light passing through a narrow slit can create a diffraction pattern on a screen. D Light is refracted when crossing a boundary between materials with different indices of refraction.
C and D
An electron is confined in the box shown in the figure and is moving back and forth in the x-direction. The electron forms a standing wave in the box. What is the longest possible wavelength of the electron's wave? A L/2L/2 B LL C 2L2L D 4L4L
C) 2L
If an object with a mass of 1kg is completely converted to energy, approximately how long could it power a 100W lightbulb? A A month B 10 years C Tens of millions of years D Thousands of millions of years
C)Tens of millions of years
Ultraviolet light with wavelength λ is shined on plate C, as shown in the figure. Electrons are ejected from plate C with a maximum kinetic energy K and reach plate A. If the power supply is set at a potential difference V, can the maximum speed of the electrons as they hit Plate A be determined, and why or why not? A Yes, because by conservation of energy, KK is equal to the energy of the photons minus the work function of the metal in plate CC. B Yes, because by conservation of energy, the kinetic energy of the electrons that reach plate AA is equal to KK minus the work done on the electrons by the field between the plates. C No, because the work function of the metal in plate CC is not known, so conservation of energy cannot be applied. D No, because the current in the connecting wires is not measured.
B) Yes, because by conservation of energy, the kinetic energy of the electrons that reach plate AA is equal to KK minus the work done on the electrons by the field between the plates.
In classical physics, relative motion is absolute. For example, consider an object moving in a straight line with speed v0 on a platform. If the platform is moving with speed vp in the same direction relative to the ground, the object will be moving with speed v0+vp relative to the ground. However, it is known that the speed of light is the same for all observers regardless of reference frame, which contradicts the classical model of relative motion. Which of the following statements is a conclusion that could be drawn from this contradiction? Select two answers. A There are no absolute reference frames. B All physical quantities are the same in all reference frames. C Light can be described by a wave model and a particle model. D Observers in different reference frames will measure time and distance differently.
A and D
Electron 1 is traveling with velocity v⃗ when it collides head on and elastically with electron 2 that is traveling with velocity −2v⃗ . Immediately after the collision, electron 1 has velocity V⃗ 1 and electron 2 has velocity V⃗ 2. Which of the following is a correct set of equations to determine V⃗ 1 and V⃗ 2 ? A v+2v=V1+V2, v^2+(2v)^2=V1^2+V2^2 B v+2v=V1+V2, v^2−(2v)^2=V1^2+V2^2 C v−2v=V1+V2, v^2+(2v)^2=V1^2+V2^2 D v−2v=V1+V2, v^2−(2v)^2=V1^2+V2^2
C) v−2v=V1+V2, v^2+(2v)^2=V1^2+V2^2
The energy levels of the Bohr model for the atom can be expressed mathematically as En=−13.6Z2n2eV, where Z is the atomic number, and n is the quantum number. This model is reasonably accurate for hydrogen and for singly ionized helium. Which of the following describes the change in kinetic energy K of the electron and the change in potential energy U of the singly ionized helium atom when the electron transitions from the ground state to the first excited state?
K-decreases U-Increases
Which of the following identifies the force that keeps protons from repelling each other in a stable nucleus? A) Gravitational force B) Strong force C) Magnetic force D) Electric force
B) Strong force
A student prepares the setup shown in the figure and then shines low-intensity ultraviolet light on metal plate C. When no potential difference is applied to the circuit, the ammeter still registers electric current. How will the ammeter reading be affected if the potential difference is gradually increased? A The current will increase as Vpowersupply is increased. B The current will decrease and will stay zero after a certain Vpowersupply value. C The current will decrease and reach zero, and as Vpowersupply is further increased the current will increase again. D The current will stay the same regardless of how much Vpowersupply is applied.
B) The current will decrease and will stay zero after a certain Vpowersupply value.
Light incident on a metal plate ejects electrons, which flow in a circuit as current. The potential difference needed to stop this current is plotted on the graph as a function of the frequency of the light. Which of the following statements about the graph is true? A The graph demonstrates conservation of energy since it shows that the energy of the incident photons is equal to the kinetic energy of the emitted electrons. B The graph demonstrates conservation of energy since it shows that the kinetic energy of the emitted electrons is different from the energy of the incident photons by a constant amount. C The graph demonstrates conservation of momentum since it shows that the momentum of the incident photons is equal to the momentum of the corresponding emitted electrons. D The graph demonstrates conservation of momentum since it shows that the momentum of the emitted electrons is different from the momentum of the incident photons by a constant amount.
B) The graph demonstrates conservation of energy since it shows that the kinetic energy of the emitted electrons is different from the energy of the incident photons by a constant amount.
An electron beam is projected at a crystal, as shown in the diagram. The signal on the other side of the crystal is recorded on a screen. A student claims this is evidence that the electrons can exhibit wave properties. Which of the following statements justifies the claim? A A signal from the electrons passes through the crystal. B The pattern of signal intensity on the screen has bright and dark areas. C The pattern of the signal intensity on the screen is similar to the interference pattern of electromagnetic radiation passing through narrow slits. D The spread of the pattern of the signal intensity on the screen is different for crystals of different interatomic spacing.
B) The pattern of signal intensity on the screen has bright and dark areas.
A nuclear power plant uses nuclear fission to convert mass into heat energy, which is then converted into electrical energy. Estimate the order of magnitude of the amount of mass converted into energy in one year in a typical nuclear power plant generating an average output electrical power of 300 MW. Assume that 35% of the energy obtained from the fission is converted to electric energy. A 10^−1 kg B 10^5 kg C 10^8 kg D 10^16 kg
A) 10^−1 kg
An unstable atom of radium (atomic mass ≈226u) is initially at rest. It decays into radon (atomic mass ≈222 u) and an alpha particle (atomic mass ≈4u). After the decay, the alpha particle travels with a speed that is 10% the speed of light. What is the speed at which radon travels after the decay process? A 0.00177c B 0.00180c C 0.09823c D 0.10180c
B) 0.00180c
A silver atom at rest has a mass of about 1.8×10−25kg. What is the rest energy of a silver atom? A 2.0×10−42J B 1.8×10−25J C 5.4×10−17J D 1.6×10−8J
D) 1.6×10−8J (E=mc^2)
A thorium nucleus of mass M=3.85×10−25kg is traveling in the +x-direction with vi=600m/s . The thorium nucleus then undergoes gamma decay, in which a gamma ray photon is emitted with wavelength λγ=0.004nm , in the +x-direction as shown in the figure. Which of the following gives the best estimate for the final velocity vf of the thorium nucleus after the photon is emitted? A 170m/s B 430m/s C 600m/s D 1030m/s
A) 170m/s Pth =M*V -pγ=h/λ
A scientist proposes sequentially detonating several thermonuclear devices as a method for deflecting an asteroid that is traveling toward Earth. The detonation of each thermonuclear device releases approximately 5.021×1015 J. How much mass must each device convert into energy? A 5.58×10^−2kg B 1.67×107kg C 5.58×1032kg D 1.67×1024kg
A) 5.58×10^−2kg
Beams of monochromatic light are emitted from two sources. Light from source A has half the wavelength of light from source B. Which of the following correctly compares the energy E of photons emitted by A to the energy of photons emitted by B and includes a correct justification? A EA=2EB, because the energy of photons is inversely proportional to the wavelength of the light. B EA=12EB, because the energy of photons is proportional to the wavelength of the light. C EA=EB, because the energy of photons, like the speed of light, is independent of their wavelength. D EA=14EB, because the energy of photons is inversely proportional to the square of the wavelength.
A) EA=2EB, because the energy of photons is inversely proportional to the wavelength of the light.
The figure shows some energy levels of hydrogen. If the magnitude of the elementary charge were 10e instead of e, how would the ground state energy of hydrogen be affected? A) It would have a much larger magnitude. B) It would have a much smaller magnitude. C) It would be the same. D) It would depend on which energy state the atom is actually in.
A) It would have a much larger magnitude.
Light of wavelength λ that delivers energy at a rate R will not eject electrons from a certain metal. Increasing the rate of energy delivery without changing the wavelength has no effect. Light of wavelength λ/2 that delivers energy at a rate R does cause electrons to be ejected from the metal. Which of the following claims can be made based on this result? A Light is behaving as a wave in this case. B Light is behaving as a particle in this case. C Light is behaving as both a particle and a wave in this case. D This experiment provides no information on the nature of light.
B) Light is behaving as a particle in this case.
Electromagnetic radiation interacts with hydrogen in the outer layers of the Sun. To completely ionize a hydrogen atom in its ground state, the atom must absorb 13.6eV of energy. The energy of any nth allowed state of hydrogen in eV is En=−13.6/n^2. Photons from inside the Sun strike hydrogen atoms in an outer layer of the Sun's upper atmosphere. In the solar absorption spectrum, there is a dark line associated with a wavelength of 486nm. Which of the following statements gives the correct energy of a photon of this wavelength and describes the creation of the corresponding absorption line? A The atom absorbs the photon's energy, equal to 2.55eV, transitioning from the state n =2 to n =4, so the continuum spectrum observed from the interior of the Sun is missing this wavelength. B The atom absorbs the photon's energy, equal to 2.55eV, transitioning from the state n =2 to n =4, and the electron then falls to its ground state, creating a bright line in that area of the spectrum. C The atom absorbs the photon's energy, equal to 0.85eV, transitioning from the state n =2 to n =4, so the continuum spectrum observed from the interior of the Sun is missing this wavelength. D The atom absorbs the photon's energy, equal to 0.85eV, transitioning from the state n =2 to n =4, and the electron then falls to its ground state, creating a bright line in that area of the spectrum.
A) The atom absorbs the photon's energy, equal to 2.55eV, transitioning from the state n =2 to n =4, so the continuum spectrum observed from the interior of the Sun is missing this wavelength.
Samples of different elements are individually held in a flame. How are the energy-level transitions of the atoms of the elements manifested in the properties of the flame? A) The colors of the flames are different, corresponding to the wavelengths of the light emitted as the atoms make transitions between states. B) The colors of the flames are different, corresponding to photons that have the same amount of energy as the atoms' highest energy state. C) The sizes of the flames are different, corresponding to the difference in energy between the atoms' states. D) The sizes of the flames are different, corresponding to the magnitude of the energy required to ionize the atoms.
A) The colors of the flames are different, corresponding to the wavelengths of the light emitted as the atoms make transitions between states.
he diagram represents a beam of green light diffracting through an opening 400nm wide. Which of the following will produce a similar pattern on the screen? A Beam of electrons with speeds v=1×106m/sv=1×106m/s B Beam of electrons with speeds v=1800m/sv=1800m/s C Emission from electrons transitioning between energy levels Ei=−5.2eVEi=−5.2eV to Ef=−8.3eVEf=−8.3eV D Emission from electrons transitioning between energy levels Ei=−5.2eVEi=−5.2eV to Ef=−2.1eV
B and C
A photon of wavelength λ0 moving to the right collides with an atom of mass M moving to the left with speed v0, as shown in the figure. Afterward, a photon of wavelength λf is moving to the left and the atom of mass M is moving to the right with speed vf. Which of the following indicates a principle that must be used to solve for the final quantities λf and vf and justifies its use? Select two answers. A Conservation of mass, because the mass of the atom is the same after the collision. B Conservation of linear momentum, because linear momentum is always conserved when no external force is exerted on a system. C Conservation of charge, because the photon has no charge. D Conservation of total energy, because mass-energy cannot be created or destroyed.
B and D
The graphs show the probability of an electron being located at a distance r from the nucleus of a hydrogen atom. The top graph represents the ground state of the atom, and the bottom graph represents the first exited state of the atom. Which of the following statements are supported by the graphs? Select two answers. A A hydrogen atom in the ground state will always have an electron closer to the nucleus than a hydrogen atom in the first excited state. B A hydrogen atom in the first excited state is more likely to have an electron further from the nucleus than a hydrogen atom in the ground state. C A hydrogen atom can simultaneously be in the ground state and in the first excited state. D A hydrogen atom in the ground state has a nonzero probability of its electron being found at any finite distance from the nucleus.
B and D
In a laboratory, two protons are projected toward each other with the same speed, as shown. Which of the following best shows the paths of the protons as they approach and then move away from each other?
B) (can't depict sorry) As depicted in the figure, the total momentum in the vertical direction is conserved and the total momentum in the horizontal direction is conserved. Also, due to the repulsive electric forces, the two protons will not get too close to each other and will follow more of a curved path than a straight one. (they are constantly pushing away from another so a curved but less extreme path)
Electromagnetic radiation interacts with hydrogen in the outer layers of the Sun. To completely ionize a hydrogen atom in its ground state, the atom must absorb 13.6eV of energy. The energy of any nth allowed state of hydrogen in eV is En=−13.6/n^2. In an outer layer of the Sun, a high-energy gamma ray interacts with an atomic nucleus and becomes an electron-positron pair. The positron has the same mass as the electron. What is the minimum possible energy of the gamma ray in electron volts? A 1.64×10−13eV B 1.02×106eV C 9.88×1013eV D 2.47×1020eV
B) 1.02×106eV
2H23e→2H11+H24e A scientist researching nuclear fusion is studying the reaction above in which two helium-3 nuclei react to form two hydrogen nuclei and a helium-4 nucleus. The scientist determines that the total mass of the two helium-3 nuclei is 1.00156×10−26 kg and that the total mass of the two hydrogen nuclei and the helium-4 nucleus is 9.9596×10−27 kg. How much energy is released in this reaction? A 5.60×10^−29 J B 5.04×10^−12 J C 8.95×10^−10 J D 9.00×10^−10 J
B) 5.04×10^−12 J (E=mc^2)
The Bohr model of the hydrogen atom proposed that the waves of the orbiting electron form a standing wave pattern. Which of the following describes the application of this model that led to discrete energy levels for the atom? A The energy of the electron depends on its mass and velocity, which together determine the energy of the states. B A whole number of wavelengths must fit in the circumference of the electron's orbit, which limits the size of the orbit to certain values. C The physical size of the electron affects its energy and thus its de Broglie wavelength, which limits the number of possible energy states. D The ratio of the mass of the electron to that of the proton affects the electron's energy and thus its de Broglie wavelength, which limits the number of possible energy states.
B) A whole number of wavelengths must fit in the circumference of the electron's orbit, which limits the size of the orbit to certain values.
A beam of electrons, all with the same speed, is incident on a crystal whose atoms are at a fixed spacing. The electrons then strike a detection screen, resulting in a diffraction pattern with alternating areas of minimum/maximum intensity similar to a double slit interference pattern. If the potential difference used to accelerate the electrons is increased, which of the following predictions is correct about the spacing between the maxima change? A The spacing decreases because as potential difference increases, so do the kinetic energy and momentum of the electrons, resulting in a longer wavelength. B The spacing decreases because as potential difference increases, so do the kinetic energy and momentum of the electrons resulting in a shorter wavelength. C The spacing increases because as potential difference increases, so do the kinetic energy and momentum of the electrons, resulting in a longer wavelength. D The spacing increases because as potential difference increases, so do the kinetic energy and momentum of the electrons resulting in a shorter wavelength.
B) The spacing decreases because as potential difference increases, so do the kinetic energy and momentum of the electrons resulting in a shorter wavelength.
A proton is placed at rest in a uniform electric field. When the proton is released, it accelerates through a distance d, acquiring a speed v as a result. Next, an alpha particle is released from rest in the field and accelerates through the same distance. The speed acquired by the alpha particle is most nearly A v/2 B √v/2 C √2v D 2v
B) √v/2 An alpha particle consists of two protons and two neutrons. Hence, because it has twice the charge of the individual proton, it obtained twice the energy when accelerated through the distance d in the uniform electric field. But the alpha particle has approximately 4 times the mass of the proton, so its speed is less.
The figure shows some of the energy levels for a hypothetical atom. A photon of wavelength 487nm has an energy of 2.55eV. Which of the following correctly indicates whether the absorption spectrum of a collection of these atoms will have a dark line at 487nm and describes a feature of the model that indicates this? (The absorption spectrum does not include any process that ionizes the atom.) A Yes. The atom has energy levels that have magnitudes less than 2.55eV. B Yes. The atom has an energy level that is exactly the same energy as a 487nm photon. C No. The atom does not have a transition between levels with an energy difference equal to the energy of a 487nm photon. D No. The atom has only one level that is an integer multiple of 2.55eV.
C) No. The atom does not have a transition between levels with an energy difference equal to the energy of a 487nm photon.
A stationary proton captures an electron of known speed, creating a hydrogen atom. No external forces act on the particles. Which of the following gives a correct method for determining the kinetic energy of the hydrogen atom and justifies the method? A Calculate the kinetic energy of the electron, which equals the kinetic energy of the hydrogen atom because the collision is elastic. B Reason that since the electron mass is much smaller than the proton mass, the motion of the electron will not affect the final motion of the hydrogen atom. C Set the momentum of the electron equal to the momentum of the hydrogen atom and determine the speed of the hydrogen, because the collision is inelastic and only momentum is conserved. Use that speed to calculate the kinetic energy of the hydrogen atom. D Measure the coulomb force that the proton exerts on the electron, and calculate the work done on the electron. This work equals the kinetic energy of the hydrogen atom.
C) Set the momentum of the electron equal to the momentum of the hydrogen atom and determine the speed of the hydrogen, because the collision is inelastic and only momentum is conserved. Use that speed to calculate the kinetic energy of the hydrogen atom.
A stationary Phosphorus-31 atom captures a slow-moving neutron of known speed, creating an atom of Phosphorus-32. No external forces act on the particles. Which of the following gives a correct method to determine the kinetic energy of the Phosphorus-32 atom and justifies the method? A Calculate the kinetic energy of the neutron, which equals the kinetic energy of the Phosphorus-32 because the collision is elastic. B Reason that Phosphorus-32 has no kinetic energy, because the collision is inelastic and the neutron is moving slowly. C Set the momentum of the neutron equal to the momentum of the Phosphorus-32 and determine the speed of the phosphorus, because the collision is inelastic and only momentum is conserved. Use that speed to calculate the kinetic energy of the Phosphorus-32. D Measure the forces that the Phosphorus-31 and the neutron exert on each other, and calculate the work they do on each other. This work equals the kinetic energy of the Phosphorus-32, because internal energy of a system is conserved.
C) Set the momentum of the neutron equal to the momentum of the Phosphorus-32 and determine the speed of the phosphorus, because the collision is inelastic and only momentum is conserved. Use that speed to calculate the kinetic energy of the Phosphorus-32.
An electron traveling at vi hits a tungsten plate and scatters with a final speed of vf, where vf<<vi. In this process an x-ray with a wavelength of λx is emitted. Which of the following is equal to the energy of the x-ray photon? A The change in the momentum of the electron B The change in the kinetic energy of the electron C The change in the internal energy of the electron D The change in the rest mass energy of the electron
C) The change in the internal energy of the electron
In an experiment to investigate the photoelectric effect, monochromatic light is shined on a metal plate. Electrons emitted from the metal move across a vacuum to a collector plate, as shown in the diagram. As the potential difference of the power supply increases, the number of electrons detected by the ammeter decreases. The potential difference is increased until it reaches Vs, at which no electrons reach the collector plate. When the potential difference is set to Vs , which of the following claims is correct about the emitted electrons? A The electric field between the two plates exerts a force on the emitted electrons, so they remain suspended between the two plates. B Electrons that were already emitted now accumulate on the collector plate, repelling the newly emitted electrons, so no new electrons are collected. C The electric field between the two plates does negative work on the emitted electrons, so they never reach the collector plate. D The potential at the metal plate overwhelms the kinetic energy of the emitted electrons, so no electrons are emitted.
C) The electric field between the two plates does negative work on the emitted electrons, so they never reach the collector plate.
When a californium (Cf) nucleus undergoes spontaneous fission, the following two reactions occur, where X and Y are unidentified nuclei. Cf98252→X+Ru44108+4n01X→Y+β−10 Which nucleus in the pair of equations has the greatest neutron-to-proton ratio? A Cf B Y C Ru D X
D) X
The figure shows a sketch of a photoelectric-effect experiment. Light incident on a metal ejects electrons from the metal's surface with a range of energies. The electrons hit the plate and a current is created in the circuit. The variable power supply is used to create a potential difference between the metal and the plate. There is a potential difference for which no electrons reach the plate and the current goes to zero. Which of the following justifies the use of this potential difference to determine the maximum kinetic energy of the electrons? A The potential difference changes the minimum amount of energy needed to release an electron from the material. B The potential difference changes the amount of energy imparted to the electrons by the incident light. C The gain in the electrons' potential energy caused by the potential difference equals their loss in kinetic energy. D The gain in the electrons' potential energy caused by the potential difference equals the energy of the photons of incident light.
C) The gain in the electrons' potential energy caused by the potential difference equals their loss in kinetic energy.
The energy levels of the Bohr model for the atom can be expressed mathematically as En=−13.6Z2n2eV, where Z is the atomic number, and n is the quantum number. This model is reasonably accurate for hydrogen and for singly ionized helium. The singly ionized helium atom consists of two protons, two neutrons, and one electron. Below are the masses of the atom and its constituents. Proton1.00728uNeutron1.00866uElectron5.49×10−4uSingly ionized helium4.00153u What is the most likely reason for the difference between the mass of the singly ionized helium atom and its constituent parts? A The missing mass was carried off by the electron when the atom was ionized. B The missing mass was converted to energy and carried off by a photon when the atom was ionized. C The mass was converted into the energy that holds the nucleus together when the nucleus was formed. D The missing mass was absorbed by the remaining electron.
C) The mass was converted into the energy that holds the nucleus together when the nucleus was formed.
Which of the following is part of the reason why stable heavy nuclei typically have more neutrons than protons? A) The neutrons negate the charges of some protons and thus reduce the net electric repulsion between protons. B) The neutrons increase the radius of the nucleus, which makes the protons further apart and decreases the electric repulsion between protons. C) The neutrons allow the strong force between nucleons to be great enough to counteract the electric repulsion between protons. D) The neutrons are arranged on the outside surface of the nucleus and shield the protons from external electric forces.
C) The neutrons allow the strong force between nucleons to be great enough to counteract the electric repulsion between protons.
Which of the following best describes what would happen if the strong force suddenly ceased to exist? A) The force of gravity would be the strongest fundamental force. B) Electrons would no longer be attracted to the nucleus of an atom. C) The nucleus would not be stable and its components would fly apart. D) The nucleus would collapse down to a point.
C) The nucleus would not be stable and its components would fly apart.
When monochromatic light is incident on the surface of a metal, there is a minimum frequency above which electrons are ejected from the metal, regardless of the intensity of the light. Which of the following claims is correct about which model of light best supports this observation? A The wave model, because electrons also have wave properties. B The wave model, because frequency is a property of waves, not particles. C The particle model, because each photon has an energy proportional to its frequency. D The particle model, because electrons are particles and can interact only with other particles.
C) The particle model, because each photon has an energy proportional to its frequency.
As shown in the figure, nucleus X of mass mX collides with nucleus Y of mass mY that is momentarily at rest (mX≠mY). Both nuclei then move off in the directions shown. It is unknown whether energy is lost during the interaction, but no other particles are produced. Which of the following claims is correct about which quantities must be the same before and after the collision? A The total mass of the two nuclei B The speed of nucleus XX C The total momentum of the two-nuclei system D It cannot be determined without knowing if energy was lost during the collision
C) The total momentum of the two-nuclei system
A molybdenum isotope (Z=42) undergoes beta negative decay (β−). Based upon conservation of charge, what must be the atomic number (Z) of the product? Also, what particles decay and what particles are produced during β− decay? A) Z=41; in β− decay, a neutron transforms into a proton, releasing an electron and a chargeless electron-antineutrino. B) Z=41; in β−decay, a proton transforms into a neutron, releasing an electron and a chargeless electron-antineutrino. C) Z=43; in β−decay, a neutron transforms into a proton, releasing an electron and a chargeless electron-antineutrino. D) Z=43; in β−decay, a proton transforms into a neutron, releasing an electron and a chargeless electron-antineutrino.
C) Z=43; in β−decay, a neutron transforms into a proton, releasing an electron and a chargeless electron-antineutrino.
2H23e→2H11+H24e A scientist researching nuclear fusion is studying the reaction above in which two helium-3 nuclei react to form two hydrogen nuclei and a helium-4 nucleus. The scientist determines that the total mass of the two helium-3 nuclei is 1.00156×10−26 kg and that the total mass of the two hydrogen nuclei and the helium-4 nucleus is 9.9596×10−27 kg. The scientist notes that this reaction involves a high-energy gamma ray photon. In what way is the photon associated with this reaction? A An electron transitions to a higher allowed energy state and absorbs a photon of this energy difference. B An electron transitions to a lower allowed energy state and emits a photon of this energy difference. C A nucleus transitions to a higher energy state and absorbs a photon of this energy difference. D A nucleus transitions to a lower energy state and emits a photon of this energy difference.
D) A nucleus transitions to a lower energy state and emits a photon of this energy difference.
A heavy nucleus can have many different energy states, while an electron is not considered to have internal energy. How does modeling the electron as a point particle and modeling the nucleus as many particles bound together explain why? A The models require that a nucleus is much more massive than an electron. B The models explain why the magnitude of the nucleus's charge is much greater than that of the electron's charge. C The models lead to the prediction that the radius of the nucleus is larger than that of the electron. D The models propose that the smaller particles in the nucleus are a system that can have both kinetic and potential energy, while the electron is a single fundamental particle.
D) The models propose that the smaller particles in the nucleus are a system that can have both kinetic and potential energy, while the electron is a single fundamental particle.
An emission spectrum for a hypothetical atom with a single electron is shown above. The wavelengths for the three lines A, B, and C are 248nm, 413nm, and 620nm, respectively. Which energy-level diagrams could represent the structure of this atom? Select two answers.
n=3 -5ev n=2 -3ev n=1 -0ev E=hf=hc/wavelength (they were duplicates)
