Question
Passive radiative cooling coats building roofs with a nearly perfect spectrum of this color. For 10 points each:
[10e] Name this color that is preferred in coatings that reject heat, since it ideally reflects all radiation.
ANSWER: white
[10m] The most ultrawhite paints contain an insoluble salt of barium and this polyatomic ion. This generally soluble ion has a minus-two charge and bears four oxygen atoms.
ANSWER: sulfate [accept SO4 or SO42- (“S-O-4-two-minus”); reject “sulfite”]
[10h] Barium sulfate is a great emitter because its value for this quantity is more than seven electron-volts, well above the energy of a solar photon. According to the Shockley–Queisser limit, the efficiency of photovoltaic cells is maximized when this quantity is 1.4 eVs (“e vees”).
ANSWER: electron bandgap [prompt on gap or energy gap]
<Adam Silverman, Science - Chemistry> ~22797~ <Editor: Adam Silverman>
Data
Summary
| Tournament | Edition | Exact Match? | Heard | PPB | Easy % | Medium % | Hard % |
|---|---|---|---|---|---|---|---|
| 2024 PACE NSC | 06/08/2024 | Y | 36 | 15.83 | 97% | 56% | 6% |