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.

[Q]: Passage: Glass has the ability to refract, reflect, and transmit light following geometrical optics, without scattering it. It is used in the manufacture of lenses and windows. Common glass has a refraction index around 1.5. This may be modified by adding low-density materials such as boron, which lowers the index of refraction (see crown glass), or increased (to as much as 1.8) with high-density materials such as (classically) lead oxide (see flint glass and lead glass), or in modern uses, less toxic oxides of zirconium, titanium, or barium. These high-index glasses (inaccurately known as "crystal" when used in glass vessels) cause more chromatic dispersion of light, and are prized for their diamond-like optical properties.
[A]: What can be used to make glass less dense?


[Q]: Passage: In free-range husbandry, the birds can roam freely outdoors for at least part of the day. Often, this is in large enclosures, but the birds have access to natural conditions and can exhibit their normal behaviours. A more intensive system is yarding, in which the birds have access to a fenced yard and poultry house at a higher stocking rate. Poultry can also be kept in a barn system, with no access to the open air, but with the ability to move around freely inside the building. The most intensive system for egg-laying chickens is battery cages, often set in multiple tiers. In these, several birds share a small cage which restricts their ability to move around and behave in a normal manner. The eggs are laid on the floor of the cage and roll into troughs outside for ease of collection. Battery cages for hens have been illegal in the EU since January 1, 2012.
[A]: What is the benefit to chickens of being in a caged location?


[Q]: Passage: In Du "Cubisme" Metzinger and Gleizes explicitly related the sense of time to multiple perspective, giving symbolic expression to the notion of ‘duration’ proposed by the philosopher Henri Bergson according to which life is subjectively experienced as a continuum, with the past flowing into the present and the present merging into the future. The Salon Cubists used the faceted treatment of solid and space and effects of multiple viewpoints to convey a physical and psychological sense of the fluidity of consciousness, blurring the distinctions between past, present and future. One of the major theoretical innovations made by the Salon Cubists, independently of Picasso and Braque, was that of simultaneity, drawing to greater or lesser extent on theories of Henri Poincaré, Ernst Mach, Charles Henry, Maurice Princet, and Henri Bergson. With simultaneity, the concept of separate spatial and temporal dimensions was comprehensively challenged. Linear perspective developed during the Renaissance was vacated. The subject matter was no longer considered from a specific point of view at a moment in time, but built following a selection of successive viewpoints, i.e., as if viewed simultaneously from numerous angles (and in multiple dimensions) with the eye free to roam from one to the other.
[A]:
In Du Cubisme who so Metzinger and Gleizes not relate the sense of time to?