This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

[EX Q]: Passage: In Ancient Greece, green and blue were sometimes considered the same color, and the same word sometimes described the color of the sea and the color of trees. The philosopher Democritus described two different greens; cloron, or pale green, and prasinon, or leek green. Aristotle considered that green was located midway between black, symbolizing the earth, and white, symbolizing water. However, green was not counted among of the four classic colors of Greek painting; red, yellow, black and white, and is rarely found in Greek art.
[EX A]: How many blues did Democritus describe?

[EX Q]: Passage: Other widely used alloys that contain zinc include nickel silver, typewriter metal, soft and aluminium solder, and commercial bronze. Zinc is also used in contemporary pipe organs as a substitute for the traditional lead/tin alloy in pipes. Alloys of 85–88% zinc, 4–10% copper, and 2–8% aluminium find limited use in certain types of machine bearings. Zinc is the primary metal used in making American one cent coins since 1982. The zinc core is coated with a thin layer of copper to give the impression of a copper coin. In 1994, 33,200 tonnes (36,600 short tons) of zinc were used to produce 13.6 billion pennies in the United States.
[EX A]: What has zinc been replaced with in pipe organs?

[EX Q]: Passage: Carriers have evolved since their inception in the early twentieth century from wooden vessels used to deploy balloons to nuclear-powered warships that carry dozens of aircraft, including fighter jets and helicopters. As of 3 March 2016, there are thirty-seven active aircraft carriers in the world within twelve navies. The United States Navy has 10 large nuclear-powered carriers (known as supercarriers, carrying up to 90 aircraft each), the largest carriers in the world; the total deckspace is over twice that of all other nations' combined. As well as the supercarrier fleet, the US Navy has nine amphibious assault ships used primarily for helicopters (sometimes called helicopter carriers); these can also carry up to 25 fighter jets, and in some cases, are as large as some other nations' fixed-wing carriers.
[EX A]:
What were carriers used for in the early 19th century?