QUES: In principle, the Planck constant could be determined by examining the spectrum of a black-body radiator or the kinetic energy of photoelectrons, and this is how its value was first calculated in the early twentieth century. In practice, these are no longer the most accurate methods. The CODATA value quoted here is based on three watt-balance measurements of KJ2RK and one inter-laboratory determination of the molar volume of silicon, but is mostly determined by a 2007 watt-balance measurement made at the U.S. National Institute of Standards and Technology (NIST). Five other measurements by three different methods were initially considered, but not included in the final refinement as they were too imprecise to affect the result.

How was the Planck constant calculated in the early 20th century?
What is the answer?
ANS: the Planck constant could be determined by examining the spectrum of a black-body radiator or the kinetic energy of photoelectrons
QUES: In 1870, following the stunning defeat of the French Army by the Germans in the Franco-Prussian War, French workers and socialist revolutionaries seized Paris and created the Paris Commune. The Commune lasted for two months before it was crushed by the French Army, with much bloodshed. The original red banners of the Commune became icons of the socialist revolution; in 1921 members of the French Communist Party came to Moscow and presented the new Soviet government with one of the original Commune banners; it was placed (and is still in place) in the tomb of Vladimir Lenin, next to his open coffin.

After Paris was seized as a result of the Franco-Prussian war, what did revolutionaries and workers create?
What is the answer?
ANS: the Paris Commune
QUES: The elimination of wolves from Yellowstone National Park had profound impacts on the trophic pyramid. Without predation, herbivores began to over-graze many woody browse species, affecting the area's plant populations. In addition, wolves often kept animals from grazing in riparian areas, which protected beavers from having their food sources encroached upon. The removal of wolves had a direct effect on beaver populations, as their habitat became territory for grazing. Furthermore, predation keeps hydrological features such as creeks and streams in normal working order. Increased browsing on willows and conifers along Blacktail Creek due to a lack of predation caused channel incision because they helped slow the water down and hold the soil in place.

Where did beavers keep animals from grazing?
What is the answer?
ANS:
unanswerable