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 use of alloys by humans started with the use of meteoric iron, a naturally occurring alloy of nickel and iron. It is the main constituent of iron meteorites which occasionally fall down on Earth from outer space. As no metallurgic processes were used to separate iron from nickel, the alloy was used as it was. Meteoric iron could be forged from a red heat to make objects such as tools, weapons, and nails. In many cultures it was shaped by cold hammering into knives and arrowheads. They were often used as anvils. Meteoric iron was very rare and valuable, and difficult for ancient people to work.

SOLUTION: What was the first man-made alloy used by humans?

PROBLEM: Passage: At present the A35 autoroute, which parallels the Rhine between Karlsruhe and Basel, and the A4 autoroute, which links Paris with Strasbourg, penetrate close to the centre of the city. The Grand contournement ouest (GCO) project, programmed since 1999, plans to construct a 24 km (15 mi) long highway connection between the junctions of the A4 and the A35 autoroutes in the north and of the A35 and A352 autoroutes in the south. This routes well to the west of the city and is meant to divest a significant portion of motorized traffic from the unité urbaine.

SOLUTION: What does the A35 link Strasbourg with?

PROBLEM: Passage: The 2008 Research Assessment Exercise returned 26% of the 1225 staff submitted as being world-leading (4*) and a further 47% as being internationally excellent (3*). The 2008 Research Assessment Exercise also showed five subjects – Pure Mathematics, Epidemiology and Public Health, Chemical Engineering, Civil Engineering, and Mechanical, Aeronautical and Manufacturing Engineering – were assessed to be the best[clarification needed] in terms of the proportion of internationally recognised research quality.

SOLUTION:
what assesment showed 1225 staff to be world-leading?