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: Claiming the right to name his discovery, Le Verrier quickly proposed the name Neptune for this new planet, though falsely stating that this had been officially approved by the French Bureau des Longitudes. In October, he sought to name the planet Le Verrier, after himself, and he had loyal support in this from the observatory director, François Arago. This suggestion met with stiff resistance outside France. French almanacs quickly reintroduced the name Herschel for Uranus, after that planet's discoverer Sir William Herschel, and Leverrier for the new planet.

SOLUTION: What name was opposed by the french?

PROBLEM: Passage: Tajikistan is landlocked, and is the smallest nation in Central Asia by area. It lies mostly between latitudes 36° and 41° N (a small area is north of 41°), and longitudes 67° and 75° E (a small area is east of 75°). It is covered by mountains of the Pamir range, and more than fifty percent of the country is over 3,000 meters (9,800 ft) above sea level. The only major areas of lower land are in the north (part of the Fergana Valley), and in the southern Kofarnihon and Vakhsh river valleys, which form the Amu Darya. Dushanbe is located on the southern slopes above the Kofarnihon valley.

SOLUTION:
Which country is the largest nation in Central Asia by area?