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: In the floor, just inside the great west door, in the centre of the nave, is the tomb of The Unknown Warrior, an unidentified British soldier killed on a European battlefield during the First World War. He was buried in the abbey on 11 November 1920. This grave is the only one in the abbey on which it is forbidden to walk.[citation needed]

SOLUTION: When was The Known Warrior buried?

PROBLEM: Passage: Unveiled in 1888, Royal Arsenal's first crest featured three cannon viewed from above, pointing northwards, similar to the coat of arms of the Metropolitan Borough of Woolwich (nowadays transferred to the coat of arms of the Royal Borough of Greenwich). These can sometimes be mistaken for chimneys, but the presence of a carved lion's head and a cascabel on each are clear indicators that they are cannon. This was dropped after the move to Highbury in 1913, only to be reinstated in 1922, when the club adopted a crest featuring a single cannon, pointing eastwards, with the club's nickname, The Gunners, inscribed alongside it; this crest only lasted until 1925, when the cannon was reversed to point westward and its barrel slimmed down.

SOLUTION: In what year did the Metropolitan Borough of Woolwich develop its coat of arms?

PROBLEM: Passage: Stars, planets, and moons keep their atmospheres by gravitational attraction, and as such, atmospheres have no clearly delineated boundary: the density of atmospheric gas simply decreases with distance from the object. The Earth's atmospheric pressure drops to about 6998320000000000000♠3.2×10−2 Pa at 100 kilometres (62 mi) of altitude, the Kármán line, which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar winds, so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre.

SOLUTION:
What is commonly known as the boundary of the Sun?