Problem: Incandescent light bulb:

In a conventional lamp, the evaporated tungsten eventually condenses on the inner surface of the glass envelope, darkening it. For bulbs that contain a vacuum, the darkening is uniform across the entire surface of the envelope. When a filling of inert gas is used, the evaporated tungsten is carried in the thermal convection currents of the gas, depositing preferentially on the uppermost part of the envelope and blackening just that portion of the envelope. An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory, when tested according to IEC Publication 60064. Light loss is due to filament evaporation and bulb blackening. Study of the problem of bulb blackening led to the discovery of the Edison effect, thermionic emission and invention of the vacuum tube.

What lightens a conventional bulb?
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A: unanswerable

Problem: The success of the show's alumni however has led to a more positive assessment of the show, and the show was described as having "proven it has a valid way to pick talent and a proven way to sell records". While the industry is divided on the show success, its impact is felt particularly strongly in the country music format. According to a CMT exec, reflecting on the success of Idol alumni in the country genre, "if you want to try and get famous fast by going to a cattle call audition on TV, Idol reasonably remains the first choice for anyone," and that country music and Idol "go together well".
Which music genre has had the most success from American Idol?
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Answer: country

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The Royal School of Mines was established by Sir Henry de la Beche in 1851, developing from the Museum of Economic Geology, a collection of minerals, maps and mining equipment. He created a school which laid the foundations for the teaching of science in the country, and which has its legacy today at Imperial. Prince Albert was a patron and supporter of the later developments in science teaching, which led to the Royal College of Chemistry becoming part of the Royal School of Mines, to the creation of the Royal College of Science and eventually to these institutions becoming part of his plan for South Kensington being an educational region.
Who wanted to make North Kensington an education region?
A: unanswerable

Context and question: Popes called for crusades to take place elsewhere besides the Holy Land: in Spain, southern France, and along the Baltic. The Spanish crusades became fused with the Reconquista of Spain from the Muslims. Although the Templars and Hospitallers took part in the Spanish crusades, similar Spanish military religious orders were founded, most of which had become part of the two main orders of Calatrava and Santiago by the beginning of the 12th century. Northern Europe also remained outside Christian influence until the 11th century or later, and became a crusading venue as part of the Northern Crusades of the 12th to 14th centuries. These crusades also spawned a military order, the Order of the Sword Brothers. Another order, the Teutonic Knights, although originally founded in the crusader states, focused much of its activity in the Baltic after 1225, and in 1309 moved its headquarters to Marienburg in Prussia.
In what century did the Northern Crusades begin?
Answer: 12th

Question: During the 16th century locally produced wool was the major export commodity. Plymouth was the home port for successful maritime traders, among them Sir John Hawkins, who led England's first foray into the Atlantic slave trade, as well as Sir Francis Drake, Mayor of Plymouth in 1581 and 1593. According to legend, Drake insisted on completing his game of bowls on the Hoe before engaging the Spanish Armada in 1588. In 1620 the Pilgrim Fathers set sail for the New World from Plymouth, establishing Plymouth Colony the second English colony in what is now the United States of America.
Is there an answer to this question: What was the name of the settlement founded by the Pilgrim Fathers?

Answer: Plymouth Colony

In the late 19th century, three European-American middle-class female teachers married Indigenous American men they had met at Hampton Institute during the years when it ran its Indian program. In the late nineteenth century, Charles Eastman, a physician of European and Sioux ancestry who trained at Boston University, married Elaine Goodale, a European-American woman from New England. They met and worked together in Dakota Territory when she was Superintendent of Indian Education and he was a doctor for the reservations. His maternal grandfather was Seth Eastman, an artist and Army officer from New England, who had married a Sioux woman and had a daughter with her while stationed at Fort Snelling in Minnesota.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Who was a lawyer of European and Sioux ancestry?
Ah, so..
unanswerable