instruction:
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.
question:
Passage: Due to its location, the Punjab region came under constant attacks and influence from the west and witnessed centuries of foreign invasions by the Greeks, Kushans, Scythians, Turks, and Afghans. The city of Taxila, founded by son of Taksh the son Bharat who was the brother of Ram. It was reputed to house the oldest university in the world,[citation needed] Takshashila University. One of the teachers was the great Vedic thinker and politician Chanakya. Taxila was a great centre of learning and intellectual discussion during the Maurya Empire. It is a UN World Heritage site, valued for its archaeological and religious history.
answer:
Who has Punjab invaded?

question:
Passage: After the Peace of Westphalia, several border territories were assigned to the United Provinces. They were federally-governed Generality Lands (Generaliteitslanden). They were Staats-Brabant (present North Brabant), Staats-Vlaanderen (present Zeeuws-Vlaanderen), Staats-Limburg (around Maastricht) and Staats-Oppergelre (around Venlo, after 1715).
answer:
In 1715 what was assigned to the United Provinces?

question:
Passage: With the introduction of the blast furnace to Europe in the Middle Ages, pig iron was able to be produced in much higher volumes than wrought iron. Because pig iron could be melted, people began to develop processes of reducing the carbon in the liquid pig iron to create steel. Puddling was introduced during the 1700s, where molten pig iron was stirred while exposed to the air, to remove the carbon by oxidation. In 1858, Sir Henry Bessemer developed a process of steel-making by blowing hot air through liquid pig iron to reduce the carbon content. The Bessemer process was able to produce the first large scale manufacture of steel. Once the Bessemer process began to gain widespread use, other alloys of steel began to follow. Mangalloy, an alloy of steel and manganese exhibiting extreme hardness and toughness, was one of the first alloy steels, and was created by Robert Hadfield in 1882.
answer:
What allowed wrought iron to be produced in larger quantities than pig iron during the Middle Ages?