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: Selenizza is a naturally occurring solid hydrocarbon bitumen found in the native asphalt deposit of Selenice, in Albania, the only European asphalt mine still in use. The rock asphalt is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring & ball) around 120 °C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.

SOLUTION: The soluble matter consists mainly of silica ore and ranges from what percentage?

PROBLEM: Passage: Santa Monica was long inhabited by the Tongva people. Santa Monica was called Kecheek in the Tongva language. The first non-indigenous group to set foot in the area was the party of explorer Gaspar de Portolà, who camped near the present day intersection of Barrington and Ohio Avenues on August 3, 1769. There are two different versions of the naming of the city. One says that it was named in honor of the feast day of Saint Monica (mother of Saint Augustine), but her feast day is actually May 4. Another version says that it was named by Juan Crespí on account of a pair of springs, the Kuruvungna Springs (Serra Springs), that were reminiscent of the tears that Saint Monica shed over her son's early impiety.

SOLUTION: What language did Gaspar de Portola speak?

PROBLEM: Passage: Unaspirated or tenuis consonants are occasionally marked with the modifier letter for unaspiration ⟨◌˭⟩, a superscript equal sign: ⟨t˭⟩. Usually, however, unaspirated consonants are left unmarked: ⟨t⟩.

SOLUTION:
Aspirated or tenuis consonants are occasionally marked how?