Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Passage: In 1763, Spain traded Florida to the Kingdom of Great Britain for control of Havana, Cuba, which had been captured by the British during the Seven Years' War. It was part of a large expansion of British territory following the country's victory in the Seven Years' War. Almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba. The British soon constructed the King's Road connecting St. Augustine to Georgia. The road crossed the St. Johns River at a narrow point, which the Seminole called Wacca Pilatka and the British named "Cow Ford", both names ostensibly reflecting the fact that cattle were brought across the river there.
Solution: Who owned Cuba after the Eight Years War?
Reason: This question appears to be relevant to the passage as both involves words such as 'Cuba' and 'War' which also exist in the passage. The passage mentions that "after the war, almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba". This information is not sufficient to conclude that which country owned cuba.

Now, solve this instance: Passage: Until 18 December 2010, Eton College was an exempt charity under English law (Charities Act 1993, Schedule 2). Under the provisions of the Charities Act 2006, it is now an excepted charity, and fully registered with the Charities Commission, and is now one of the 100 largest charities in the UK. As a charity, it benefits from substantial tax breaks. It was calculated by the late David Jewell, former Master of Haileybury, that in 1992 such tax breaks saved the School about 1,945 per pupil per year, although he had no direct connection with the School. This subsidy has declined since the 2001 abolition by the Labour Government of state-funded scholarships (formerly known as "assisted places") to independent schools. However, no child attended Eton on this scheme, meaning that the actual level of state assistance to the School has always been lower. Eton's retiring Head Master, Tony Little, has claimed that the benefits that Eton provides to the local community free of charge (use of its facilities, etc.) have a higher value than the tax breaks it receives as a result of its charitable status. The fee for the academic year 20102011 was 29,862 (approximately US$48,600 or 35,100 as of March 2011), although the sum is considerably lower for those pupils on bursaries and scholarships.
Student:
What is the largest charity in the UK?