Q: 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.
Passage: With two-cylinder compounds used in railway work, the pistons are connected to the cranks as with a two-cylinder simple at 90 out of phase with each other (quartered). When the double expansion group is duplicated, producing a 4-cylinder compound, the individual pistons within the group are usually balanced at 180, the groups being set at 90 to each other. In one case (the first type of Vauclain compound), the pistons worked in the same phase driving a common crosshead and crank, again set at 90 as for a two-cylinder engine. With the 3-cylinder compound arrangement, the LP cranks were either set at 90 with the HP one at 135 to the other two, or in some cases all three cranks were set at 120.[citation needed]
A:
At what degree are the pistons of a two-cylinder compound connected to the pistons?