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.

[Q]: Passage: Uranium was also used in photographic chemicals (especially uranium nitrate as a toner), in lamp filaments for stage lighting bulbs, to improve the appearance of dentures, and in the leather and wood industries for stains and dyes. Uranium salts are mordants of silk or wool. Uranyl acetate and uranyl formate are used as electron-dense "stains" in transmission electron microscopy, to increase the contrast of biological specimens in ultrathin sections and in negative staining of viruses, isolated cell organelles and macromolecules.
[A]: What product of uranium wasn't used as toner?


[Q]: Passage: The effects of local surface low pressure are extremely limited because upper-level subsidence still continues to block any form of air ascent. Also, to be protected against rain-bearing weather systems by the atmospheric circulation itself, the desert is made even drier by his geographical configuration and location. Indeed, the extreme aridity of the Sahara can't be only explained by the subtropical high pressure. The Atlas Mountains, found in Algeria, Morocco and Tunisia also help to enhance the aridity of the northern part of the desert. These major mountain ranges act as a barrier causing a strong rain shadow effect on the leeward side by dropping much of the humidity brought by atmospheric disturbances along the polar front which affects the surrounding Mediterranean climates.
[A]: what is blocked buy the surface low pressure?


[Q]: Passage: The revocation forbade Protestant services, required education of children as Catholics, and prohibited emigration. It proved disastrous to the Huguenots and costly for France. It precipitated civil bloodshed, ruined commerce, and resulted in the illegal flight from the country of hundreds of thousands of Protestants, many of whom became intellectuals, doctors and business leaders in Britain as well as Holland, Prussia, and South Africa. Four thousand emigrated to the North American colonies, where they settled in New York and Virginia, especially. The English welcomed the French refugees, providing money from both government and private agencies to aid their relocation. Those Huguenots who stayed in France became Catholics and were called "new converts".
[A]:
How many French people fled to Prussia?