TASK DEFINITION: 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.
PROBLEM: Passage: The FBI has maintained files on numerous people, including celebrities such as Elvis Presley, Frank Sinatra, John Denver, John Lennon, Jane Fonda, Groucho Marx, Charlie Chaplin, the band MC5, Lou Costello, Sonny Bono, Bob Dylan, Michael Jackson, and Mickey Mantle. The files were collected for various reasons. Some of the subjects were investigated for alleged ties to the Communist party (Charlie Chaplin and Groucho Marx), or in connection with antiwar activities during the Vietnam War (John Denver, John Lennon, and Jane Fonda). Numerous celebrity files concern threats or extortion attempts against them (Sonny Bono, John Denver, John Lennon, Elvis Presley, Michael Jackson, Mickey Mantle, Groucho Marx, and Frank Sinatra).

SOLUTION: Who has the FBI never maintained a file on?

PROBLEM: Passage: The principles of imperialism are often generalizable to the policies and practices of the British Empire "during the last generation, and proceeds rather by diagnosis than by historical description". British imperialism often used the concept of Terra nullius (Latin expression which stems from Roman law meaning 'empty land'). The country of Australia serves as a case study in relation to British settlement and colonial rule of the continent in the eighteenth century, as it was premised on terra nullius, and its settlers considered it unused by its sparse Aboriginal inhabitants.

SOLUTION:  Imperialism is less often associated with which sovereignty?

PROBLEM: Passage: The concept of legal certainty is recognised one of the general principles of European Union law by the European Court of Justice since the 1960s. It is an important general principle of international law and public law, which predates European Union law. As a general principle in European Union law it means that the law must be certain, in that it is clear and precise, and its legal implications foreseeable, specially when applied to financial obligations. The adoption of laws which will have legal effect in the European Union must have a proper legal basis. Legislation in member states which implements European Union law must be worded so that it is clearly understandable by those who are subject to the law. In European Union law the general principle of legal certainty prohibits Ex post facto laws, i.e. laws should not take effect before they are published. The doctrine of legitimate expectation, which has its roots in the principles of legal certainty and good faith, is also a central element of the general principle of legal certainty in European Union law. The legitimate expectation doctrine holds that and that "those who act in good faith on the basis of law as it is or seems to be should not be frustrated in their expectations".

SOLUTION:
What is not recognized as one of the general principles of European Union law?