Problem: Glass:

Most common glass contains other ingredients to change its properties. Lead glass or flint glass is more 'brilliant' because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index. Thorium oxide gives glass a high refractive index and low dispersion and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern eyeglasses.[citation needed] Iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs UV wavelengths.

What property of thorium oxide has caused it to no longer be used in eyeglasses?
---
A: radioactivity


Problem: A. A. Luce and John Foster are other subjectivists. Luce, in Sense without Matter (1954), attempts to bring Berkeley up to date by modernizing his vocabulary and putting the issues he faced in modern terms, and treats the Biblical account of matter and the psychology of perception and nature. Foster's The Case for Idealism argues that the physical world is the logical creation of natural, non-logical constraints on human sense-experience. Foster's latest defense of his views is in his book A World for Us: The Case for Phenomenalistic Idealism.
Who wrote A World for Us: The Case for Phenomenalistic Idealism?
---
Answer: Foster


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In 1959, an international gathering of over 185 judges, lawyers, and law professors from 53 countries, meeting in New Delhi and speaking as the International Commission of Jurists, made a declaration as to the fundamental principle of the rule of law. This was the Declaration of Delhi. They declared that the rule of law implies certain rights and freedoms, that it implies an independent judiciary, and that it implies social, economic and cultural conditions conducive to human dignity. The Declaration of Delhi did not, however, suggest that the rule of law requires legislative power to be subject to judicial review.
Who made a declaration about the principle of rule of law in the nineteenth century?
A: unanswerable


Context and question: In their attempt to ensure white supremacy decades after emancipation, in the early 20th century, most southern states created laws based on the one-drop rule, defining as black, persons with any known African ancestry. This was a stricter interpretation than what had prevailed in the 19th century; it ignored the many mixed families in the state and went against commonly accepted social rules of judging a person by appearance and association. Some courts called it "the traceable amount rule." Anthropologists called it an example of a hypodescent rule, meaning that racially mixed persons were assigned the status of the socially subordinate group.
Prior to the 1900s, what was the socially accepted rule for racial interpretation?
Answer: judging a person by appearance and association.


Question: George Dayton had founded his Dayton's Dry Goods store in Minneapolis in 1902 and the AMC cooperative in 1912. His descendants built Southdale Center in 1956, opened the Target discount store chain in 1962 and the B. Dalton Bookseller chain in 1966. Dayton's grew to 19 stores under the Dayton's name plus five other regional names acquired by Dayton-Hudson. The Dayton-Hudson Corporation closed the flagship J. L. Hudson Department Store in downtown Detroit in 1983, but expanded its other retail operations. It acquired Mervyn's in 1978, Marshall Field's in 1990, and renamed itself the Target Corporation in 2000. In 2002, Dayton's and Hudson's were consolidated into the Marshall Field's name. In 2005, May Department Stores acquired all of the Marshall Field's stores and shortly thereafter, Macy's acquired May.
Is there an answer to this question: Who closed Dayton's Dry Goods?

Answer: unanswerable


QUES: Opera debuted in 1996; it has never achieved widespread use, having less than 2% browser usage share as of February 2012 according to Net Applications. Its Opera-mini version has an additive share, in April 2011 amounting to 1.1% of overall browser use, but focused on the fast-growing mobile phone web browser market, being preinstalled on over 40 million phones. It is also available on several other embedded systems, including Nintendo's Wii video game console.

How many game consoles has Nintendo sold?
What is the answer?
ANS:
unanswerable