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: 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.

SOLUTION: What product of uranium wasn't used as toner?

PROBLEM: Passage: Gender identity forms an important part of identity in psychology, as it dictates to a significant degree how one views oneself both as a person and in relation to other people, ideas and nature. Other aspects of identity, such as racial, religious, ethnic, occupational… etc. may also be more or less significant – or significant in some situations but not in others (Weinreich & Saunderson 2003 pp26–34). In cognitive psychology, the term "identity" refers to the capacity for self-reflection and the awareness of self.(Leary & Tangney 2003, p. 3)

SOLUTION: What type of identity is less important in psychology?

PROBLEM: Passage: Zhejiang was part of the Wu during the Three Kingdoms. Wu (229–280), commonly known as Eastern Wu or Sun Wu, had been the economically most developed state among the Three Kingdoms (220–280 CE). The historical novel Romance of the Three Kingdoms records that Zhejiang had the best-equipped, strong navy force. The story depicts how the states of Wei (魏) and Shu (蜀), lack of material resources, avoided direct confrontation with the Wu. In armed military conflicts with Wu, the two states relied intensively on tactics of camouflage and deception to steal Wu's military resources including arrows and bows.

SOLUTION:
When was Zhejiang part of the Lu?