HS Sample Set 13, Round 15 from NSB
A gas tank contains 82 liters of helium at 2.7 atmospheres of pressure. Given that the temperature of the tank is 27 °C and the tank is filled with helium, then, to the nearest whole gram, how much helium is in the tank?
Acceptable Answers:
A particular reaction doubles in rate when the temperature is raised from 50 K to 100 K. To the nearest hundred joules, what is the activation energy of this reaction?
Acceptable Answers:
Two resistors of 12 Ω each are connected in parallel to a 3 A current source. In watts, how much total power is dissipated by the circuit?
Acceptable Answers:
Identify all of the following three physical quantities that are vectors: 1) Impulse; 2) Force; 3) Momentum.
Choices:
Correct Answers:
Which of the following best describes the mass of Ceres in terms of a percentage of the mass of our Moon? W) 0.001 X) 1 Y) 100 Z) 200
W: W) 0.001
X: X) 1
Y: Y) 100
Z: Z) 200
Answer: X) X) 1
A star is consistently observed to have a 1 % dip in brightness lasting for 3 hours every 3 days. Which of the following is the best explanation of this phenomenon? W) The star is an intrinsic variable X) The star is rotating Y) The star has an exoplanet Z) The observation is distorted by parallax
W: W) The star is an intrinsic variable
X: X) The star is rotating
Y: Y) The star has an exoplanet
Z: Z) The observation is distorted by parallax
Answer: Y) Y) The star has an exoplanet
A and B are statements, and B is true. Which of the following is true regarding the statement “A implies B”? W) It is true regardless of the truth value of A X) It is false regardless of the truth value of A Y) It is true only when A is true, and false otherwise Z) It is true only when A is false, and false otherwise
W: W) It is true regardless of the truth value of A
X: X) It is false regardless of the truth value of A
Y: Y) It is true only when A is true, and false otherwise
Z: Z) It is true only when A is false, and false otherwise
Answer: W) W) It is true regardless of the truth value of A
Triangle ABC has all angles with integral degree measures, and the measure of angle A equals 7 times the measure of angle B. How many possible degree measures are there for angle C?
Acceptable Answers:
What substance, which is produced by parietal cells in the stomach, is needed for the uptake of vitamin B₁₂?
Acceptable Answers:
Identify all of the following three surface receptors whose synthesis depends on V(D)J recombination: 1) Toll-like receptor; 2) T-cell receptor; 3) B-cell receptor.
Choices:
Correct Answers:
Why had chemists previously considered termolecular reactions to be insignificant? W) Termolecular reactions have high changes in entropy X) Termolecular reactions are usually endothermic Y) Termolecular reactions are forbidden by the Woodward–Hoffmann rules Z) Termolecular reactions are statistically unlikely to occur
W: W) Termolecular reactions have high changes in entropy
X: X) Termolecular reactions are usually endothermic
Y: Y) Termolecular reactions are forbidden by the Woodward–Hoffmann rules
Z: Z) Termolecular reactions are statistically unlikely to occur
Answer: Z) Z) Termolecular reactions are statistically unlikely to occur
DOE researchers recently detected the simultaneous arrival on Earth of the gravitational waves and the light emitted from a distant neutron star merger. This simultaneous arrival implies that, if a graviton particle exists, it must have a mass most similar to which of the following particles? W) Top quark X) Proton Y) Neutron Z) Photon
W: W) Top quark
X: X) Proton
Y: Y) Neutron
Z: Z) Photon
Answer: Z) Z) Photon
Arrange the following four diatomic molecules in order of increasing bond length: 1) N₂; 2) Cl₂; 3) F₂; 4) O₂.
Choices:
Correct Order:
Identify all of the following three diatomic species that have non-zero bond order: 1) H₂⁺; 2) H₂⁻; 3) H₂²⁻.
Choices:
Correct Answers:
Suppose a capacitor holds a charge Q and voltage V but is currently NOT connected to a voltage source. If a dielectric with dielectric constant 10 is inserted between the plates, then which of the following is TRUE? W) The voltage between the plates is multiplied by a factor of 10 X) The voltage between the plates is multiplied by a factor of 1/10 Y) The charge on the plates is multiplied by a factor of 10 Z) The charge on the plates is multiplied by a factor of 1/10
W: W) The voltage between the plates is multiplied by a factor of 10
X: X) The voltage between the plates is multiplied by a factor of 1/10
Y: Y) The charge on the plates is multiplied by a factor of 10
Z: Z) The charge on the plates is multiplied by a factor of 1/10
Answer: X) X) The voltage between the plates is multiplied by a factor of 1/10
Identify all of the following three observations that are consistent with the particle model of light, but not the wave model of light: 1) Compton scattering; 2) Photoelectric effect; 3) Diffraction.
Choices:
Correct Answers:
What is the dot product of the vectors 3i – 2j + k and 4i – j?
Acceptable Answers:
In a particular year, if June 6 is on a Tuesday, on what day of the week is December 7?
Acceptable Answers:
What stage of embryonic development that follows the morula is characterized as a fluid-filled sphere?
Acceptable Answers:
Identify all of the following three features that all chordates possess at some point in their development: 1) Vertebral column; 2) Pharyngeal slits; 3) Post-anal tail.
Choices:
Correct Answers:
Which of the following best describes neutron spallation at the Spallation Neutron Source? W) High-energy protons collide with a nucleus, which then emits neutrons X) High-energy neutrons collide with a nucleus, which then emits protons Y) Low-energy neutrons are absorbed by a nucleus, which splits and emits neutrons Z) High-energy neutrons are absorbed by a nucleus, which splits and emits neutrons
W: W) High-energy protons collide with a nucleus, which then emits neutrons
X: X) High-energy neutrons collide with a nucleus, which then emits protons
Y: Y) Low-energy neutrons are absorbed by a nucleus, which splits and emits neutrons
Z: Z) High-energy neutrons are absorbed by a nucleus, which splits and emits neutrons
Answer: W) W) High-energy protons collide with a nucleus, which then emits neutrons
Scientists at SLAC National Accelerator Lab are studying the properties of a calcium titanate mineral that may eventually outperform silicon-based solar cells. What is the common name of this mineral?
Acceptable Answers:
On a map of the magnetic anomalies recorded in the Earth’s oceanic crust, you will see a series of bands aligned roughly parallel to mid-ocean spreading centers representing reversals in the Earth’s magnetic field. A contour line that separates two magnetic anomalies is which of the following? W) Isochron X) Isochor Y) Isostasy Z) Isocline
W: W) Isochron
X: X) Isochor
Y: Y) Isostasy
Z: Z) Isocline
Answer: W) W) Isochron
Seismologists believe that Earth’s inner core rotates faster than the rest of the planet. What evidence do they cite? W) The fastest route for S-waves is shifting eastward over time X) The fastest route for S-waves is shifting westward over time Y) The fastest route for P-waves is shifting eastward over time Z) The fastest route for P-waves is shifting westward over time
W: W) The fastest route for S-waves is shifting eastward over time
X: X) The fastest route for S-waves is shifting westward over time
Y: Y) The fastest route for P-waves is shifting eastward over time
Z: Z) The fastest route for P-waves is shifting westward over time
Answer: Y) Y) The fastest route for P-waves is shifting eastward over time
Which of the following diseases is caused by an apicomplexan? W) Tuberculosis X) Malaria Y) Chagas disease Z) AIDS
W: W) Tuberculosis
X: X) Malaria
Y: Y) Chagas disease
Z: Z) AIDS
Answer: X) X) Malaria
D5W is a solution found in IV bags that is 5 % glucose by weight. Given that the molar mass of glucose is 180 g/mol, then expressed in milliosmoles per liter to one significant figure, what is the osmolarity of D5W?
Acceptable Answers:
A light wave is propagating along the x-axis in the positive direction. If the electric field is currently oriented toward the positive z-axis, then expressing your answer as a sign and an axis, which way is the magnetic field oriented?
Acceptable Answers:
For real gases, the difference between their molar heat capacities at constant pressure and at constant volume is equal to the ideal gas constant plus or minus some deviation. For which of the following gases is this deviation the largest? W) Helium X) Argon Y) Carbon monoxide Z) Carbon dioxide
W: W) Helium
X: X) Argon
Y: Y) Carbon monoxide
Z: Z) Carbon dioxide
Answer: Z) Z) Carbon dioxide
According to VSEPR theory, which of the following statements is TRUE concerning the trigonal bipyramidal geometry? W) The molecular geometry of BrF₅ is trigonal bipyramidal X) Lone pairs occupy equatorial positions Y) The associated central-atom hybridization is d²sp³ Z) The electron-pair geometry of CCl₄ is trigonal bipyramidal
W: W) The molecular geometry of BrF₅ is trigonal bipyramidal
X: X) Lone pairs occupy equatorial positions
Y: Y) The associated central-atom hybridization is d²sp³
Z: Z) The electron-pair geometry of CCl₄ is trigonal bipyramidal
Answer: X) X) Lone pairs occupy equatorial positions
Identify all of the following three statements that describe the dimerization reaction of butadiene: 1) It is first-order; 2) It is entropically favored; 3) The half-life increases over time.
Choices:
Correct Answers:
Which of the following statements is true of main sequence stars? W) Class A stars are the hottest X) Less-massive stars have longer lifetimes than more-massive stars Y) Less-massive stars have higher luminosities than more-massive stars Z) Red supergiants are the coolest main-sequence stars
W: W) Class A stars are the hottest
X: X) Less-massive stars have longer lifetimes than more-massive stars
Y: Y) Less-massive stars have higher luminosities than more-massive stars
Z: Z) Red supergiants are the coolest main-sequence stars
Answer: X) X) Less-massive stars have longer lifetimes than more-massive stars
A doublet of strong yellow D lines in the spectrum of the Sun are absorption lines stemming from what element?
Acceptable Answers:
What is the limit as $$x$$ approaches $$1$$ of the fraction $$\frac{x^2 - 9}{x^3 - 27}$$?
Acceptable Answers:
A right circular cone with height 8 and radius 6 is sliced halfway along its height to form a frustum. What is the lateral surface area of the frustum?
Acceptable Answers:
Scientists at Los Alamos National Lab are studying upwelling in the Southern Ocean using a combination of seawater measurements and modeling. In particular, they identified five major upwelling hotspots associated with undersea topographic features in the path of what ocean current, the largest and strongest in the globe?
Acceptable Answers:
The ICARUS detector has been moved to Fermilab for further neutrino experiments. This detector is filled with argon that, upon interaction with a neutrino, becomes what element?
Acceptable Answers:
What chemical element is in the chemical formula for dolomite, but not that for calcite?
Acceptable Answers:
An erratic, such as Big Rock in Alberta, Canada, is a large boulder whose geology differs significantly from that of its current location. What carried this erratic to its current location?
Acceptable Answers:
When comparing carbon-13 NMR to proton NMR, which of the following best explains why one rarely sees coupling between carbon nuclei in ¹³C NMR? W) Carbon-13 nuclei do not magnetically couple with one another X) Carbon-13 nuclei have no net magnetic moment Y) Carbon-13 coupling is usually compensated for with the NMR probe Z) It is rare for any given molecule to have more than one carbon-13 atom
W: W) Carbon-13 nuclei do not magnetically couple with one another
X: X) Carbon-13 nuclei have no net magnetic moment
Y: Y) Carbon-13 coupling is usually compensated for with the NMR probe
Z: Z) It is rare for any given molecule to have more than one carbon-13 atom
Answer: Z) Z) It is rare for any given molecule to have more than one carbon-13 atom
For which of the following reactions does Kₚ, the pressure equilibrium constant, equal K_c, the concentration equilibrium constant? W) H₂ (g) + Cl₂ (g) ⟶ 2 HCl (g) X) 2 H₂ (g) + O₂ (g) ⟶ 2 H₂O (g) Y) N₂ (g) + 2 O₂ (g) ⟶ 2 NO₂ (g) Z) N₂O₄ (g) ⟶ 2 NO₂ (g)
W: W) H₂ (g) + Cl₂ (g) ⟶ 2 HCl (g)
X: X) 2 H₂ (g) + O₂ (g) ⟶ 2 H₂O (g)
Y: Y) N₂ (g) + 2 O₂ (g) ⟶ 2 NO₂ (g)
Z: Z) N₂O₄ (g) ⟶ 2 NO₂ (g)
Answer: W) W) H₂ (g) + Cl₂ (g) ⟶ 2 HCl (g)
Which of Maxwell’s equations directly enforces the postulate that magnetic monopoles do not exist?
Acceptable Answers:
DO NOT ACCEPT:
An object is undergoing one-dimensional motion at time $t=0$. If its velocity equals $3e^{-2t}$, then, as time increases, what value does the total displacement of the object approach?
Acceptable Answers:
What is the sum of the zeroes of the polynomial $2x^3 + 11x^2 + 2x - 16$?
Acceptable Answers:
What is the largest prime factor of the quantity $5^{2016} + 5^{2017} + 5^{2018} + 5^{2019}$?
Acceptable Answers:
The synapsids and the reptiles were able to adapt to life on land due to what key evolutionary innovation?
Acceptable Answers:
Identify all of the following three classes of chordates that possess vertebrae: 1) Myxini; 2) Reptilia; 3) Cephalochordata.
Choices:
Correct Answers: