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.
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Question: Passage: The French population numbered about 75,000 and was heavily concentrated along the St. Lawrence River valley, with some also in Acadia (present-day New Brunswick and parts of Nova Scotia, including Île Royale (present-day Cape Breton Island)). Fewer lived in New Orleans, Biloxi, Mississippi, Mobile, Alabama and small settlements in the Illinois Country, hugging the east side of the Mississippi River and its tributaries. French fur traders and trappers traveled throughout the St. Lawrence and Mississippi watersheds, did business with local tribes, and often married Indian women. Traders married daughters of chiefs, creating high-ranking unions.

Answer: What wasn't the French population in North America?


Question: Passage: On April 12, 1980, a military coup led by Master Sergeant Samuel Doe of the Krahn ethnic group overthrew and killed President William R. Tolbert, Jr.. Doe and the other plotters later executed a majority of Tolbert's cabinet and other Americo-Liberian government officials and True Whig Party members. The coup leaders formed the People's Redemption Council (PRC) to govern the country. A strategic Cold War ally of the West, Doe received significant financial backing from the United States while critics condemned the PRC for corruption and political repression.

Answer: Who led a military coup that killed the American ambassador?


Question: Passage: Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons, uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating.

Answer:
What is the sole fissile isotope that occurs out of nature?