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.

Example Input: 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.
Example Output: What product of uranium wasn't used as toner?

Example Input: Passage: Compression is useful because it helps reduce resource usage, such as data storage space or transmission capacity. Because compressed data must be decompressed to use, this extra processing imposes computational or other costs through decompression; this situation is far from being a free lunch. Data compression is subject to a space–time complexity trade-off. For instance, a compression scheme for video may require expensive hardware for the video to be decompressed fast enough to be viewed as it is being decompressed, and the option to decompress the video in full before watching it may be inconvenient or require additional storage. The design of data compression schemes involves trade-offs among various factors, including the degree of compression, the amount of distortion introduced (when using lossy data compression), and the computational resources required to compress and decompress the data.
Example Output: What helps reduce trade-offs?

Example Input: Passage: Palmerston died in 1865, and after a brief ministry led by Russell, Derby returned to power. In 1866, Victoria attended the State Opening of Parliament for the first time since Albert's death. The following year she supported the passing of the Reform Act 1867 which doubled the electorate by extending the franchise to many urban working men, though she was not in favour of votes for women. Derby resigned in 1868, to be replaced by Benjamin Disraeli, who charmed Victoria. "Everyone likes flattery," he said, "and when you come to royalty you should lay it on with a trowel." With the phrase "we authors, Ma'am", he complimented her. Disraeli's ministry only lasted a matter of months, and at the end of the year his Liberal rival, William Ewart Gladstone, was appointed prime minister. Victoria found Gladstone's demeanour far less appealing; he spoke to her, she is thought to have complained, as though she were "a public meeting rather than a woman".
Example Output:
Who died in 1856?