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: Zinc metal is produced using extractive metallurgy. After grinding the ore, froth flotation, which selectively separates minerals from gangue by taking advantage of differences in their hydrophobicity, is used to get an ore concentrate. This concentrate consists of about 50% zinc with the rest being sulfur (32%), iron (13%), and SiO
2 (5%). The composition of this is normally zinc sulfide (80% to 85%), iron sulfide (7.0% to 12%), lead sulfide (3.0% to 5.0%) silica (2.5% to 3.5%), and cadmium sulfide (0.35% to 0.41%).
What is used to eliminate the metal zinc?

Passage: Instruction is the facilitation of another's learning. Instructors in primary and secondary institutions are often called teachers, and they direct the education of students and might draw on many subjects like reading, writing, mathematics, science and history. Instructors in post-secondary institutions might be called teachers, instructors, or professors, depending on the type of institution; and they primarily teach only their specific discipline. Studies from the United States suggest that the quality of teachers is the single most important factor affecting student performance, and that countries which score highly on international tests have multiple policies in place to ensure that the teachers they employ are as effective as possible. With the passing of NCLB in the United States (No Child Left Behind), teachers must be highly qualified. A popular way to gauge teaching performance is to use student evaluations of teachers (SETS), but these evaluations have been criticized for being counterproductive to learning and inaccurate due to student bias.
What is the opposite term used for instructors?

Passage: There are several details that are only found in one of the gospel accounts. For instance, only Matthew's gospel mentions an earthquake, resurrected saints who went to the city and that Roman soldiers were assigned to guard the tomb, while Mark is the only one to state the actual time of the crucifixion (the third hour, or 9 am) and the centurion's report of Jesus' death. The Gospel of Luke's unique contributions to the narrative include Jesus' words to the women who were mourning, one criminal's rebuke of the other, the reaction of the multitudes who left "beating their breasts", and the women preparing spices and ointments before resting on the Sabbath. John is also the only one to refer to the request that the legs be broken and the soldier's subsequent piercing of Jesus' side (as fulfillment of Old Testament prophecy), as well as that Nicodemus assisted Joseph with burial.

What time did the Romans decide to guard the tomb of Jesus?