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: 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%).
answer:
What is used to eliminate the metal zinc?


question:
Passage: Usually, a federation is formed at two levels: the central government and the regions (states, provinces, territories), and little to nothing is said about second or third level administrative political entities. Brazil is an exception, because the 1988 Constitution included the municipalities as autonomous political entities making the federation tripartite, encompassing the Union, the States, and the municipalities. Each state is divided into municipalities (municípios) with their own legislative council (câmara de vereadores) and a mayor (prefeito), which are partly autonomous from both Federal and State Government. Each municipality has a "little constitution", called "organic law" (lei orgânica). Mexico is an intermediate case, in that municipalities are granted full-autonomy by the federal constitution and their existence as autonomous entities (municipio libre, "free municipality") is established by the federal government and cannot be revoked by the states' constitutions. Moreover, the federal constitution determines which powers and competencies belong exclusively to the municipalities and not to the constituent states. However, municipalities do not have an elected legislative assembly.
answer:
When is a federation dissolved?


question:
Passage: A PM motor does not have a field winding on the stator frame, instead relying on PMs to provide the magnetic field against which the rotor field interacts to produce torque. Compensating windings in series with the armature may be used on large motors to improve commutation under load. Because this field is fixed, it cannot be adjusted for speed control. PM fields (stators) are convenient in miniature motors to eliminate the power consumption of the field winding. Most larger DC motors are of the "dynamo" type, which have stator windings. Historically, PMs could not be made to retain high flux if they were disassembled; field windings were more practical to obtain the needed amount of flux. However, large PMs are costly, as well as dangerous and difficult to assemble; this favors wound fields for large machines.
answer:

 What can a PMM motor not be adjusted for?