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.
--------
Question: Passage: The terms used to define Greekness have varied throughout history but were never limited or completely identified with membership to a Greek state. By Western standards, the term Greeks has traditionally referred to any native speakers of the Greek language, whether Mycenaean, Byzantine or modern Greek. Byzantine Greeks called themselves Romioi and considered themselves the political heirs of Rome, but at least by the 12th century a growing number of those educated, deemed themselves the heirs of ancient Greece as well, although for most of the Greek speakers, "Hellene" still meant pagan. On the eve of the Fall of Constantinople the Last Emperor urged his soldiers to remember that they were the descendants of Greeks and Romans.

Answer: What do Easterners believe it means to belong to the Greek heritage

Question: Passage: The oak forests of the southern and central Appalachians consist largely of black, northern red, white, chestnut and scarlet oaks (Quercus velutina, Q. rubra, Q. alba, Q. prinus and Q. coccinea) and hickories, such as the pignut (Carya glabra) in particular. The richest forests, which grade into mesic types, usually in coves and on gentle slopes, have dominantly white and northern red oaks, while the driest sites are dominated by chestnut oak, or sometimes by scarlet or northern red oaks. In the northern Appalachians the oaks, except for white and northern red, drop out, while the latter extends farthest north.

Answer: What is the dominate type of oak in the Appalachians?

Question: Passage: A microbrewery, or craft brewery, produces a limited amount of beer. The maximum amount of beer a brewery can produce and still be classed as a microbrewery varies by region and by authority, though is usually around 15,000 barrels (1.8 megalitres, 396 thousand imperial gallons or 475 thousand US gallons) a year. A brewpub is a type of microbrewery that incorporates a pub or other eating establishment. The highest density of breweries in the world, most of them microbreweries, exists in the German Region of Franconia, especially in the district of Upper Franconia, which has about 200 breweries. The Benedictine Weihenstephan Brewery in Bavaria, Germany, can trace its roots to the year 768, as a document from that year refers to a hop garden in the area paying a tithe to the monastery. The brewery was licensed by the City of Freising in 1040, and therefore is the oldest working brewery in the world.

Answer:
How often can a microbrewery produce 396 thousand US gallons?