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: Terra preta (black earth), which is distributed over large areas in the Amazon forest, is now widely accepted as a product of indigenous soil management. The development of this fertile soil allowed agriculture and silviculture in the previously hostile environment; meaning that large portions of the Amazon rainforest are probably the result of centuries of human management, rather than naturally occurring as has previously been supposed. In the region of the Xingu tribe, remains of some of these large settlements in the middle of the Amazon forest were found in 2003 by Michael Heckenberger and colleagues of the University of Florida. Among those were evidence of roads, bridges and large plazas.

SOLUTION: Terra preta is distributor over a small area of what?

PROBLEM: Passage: Anthrozoology (also known as "human–animal studies") is the study of interaction between living things. It is a burgeoning interdisciplinary field that overlaps with a number of other disciplines, including anthropology, ethology, medicine, psychology, veterinary medicine and zoology. A major focus of anthrozoologic research is the quantifying of the positive effects of human-animal relationships on either party and the study of their interactions. It includes scholars from a diverse range of fields, including anthropology, sociology, biology, and philosophy.[n 7]

SOLUTION: What is the study of animals?

PROBLEM: Passage: Elizabeth was born in London to the Duke and Duchess of York, later King George VI and Queen Elizabeth, and was the elder of their two daughters. She was educated privately at home. Her father acceded to the throne on the abdication of his brother Edward VIII in 1936, from which time she was the heir presumptive. She began to undertake public duties during World War II, serving in the Auxiliary Territorial Service. In 1947, she married Philip, Duke of Edinburgh, with whom she has four children: Charles, Anne, Andrew, and Edward.

SOLUTION:
In what year was Edward VIII crowned?