Problem: LaserDisc:

There were also 12 cm (4.7 in) (CD size) "single"-style discs produced that were playable on LaserDisc players. These were referred to as CD Video (CD-V) discs, and Video Single Discs (VSD). A CD-V carried up to five minutes of analog LaserDisc-type video content (usually a music video), as well as up to 20 minutes of digital audio CD tracks. The original 1989 release of David Bowie's retrospective Sound + Vision CD box set prominently featured a CD-V video of Ashes to Ashes, and standalone promo CD-Vs featured the video, plus three audio tracks: "John, I'm Only Dancing", "Changes", and "The Supermen".

What were CD-V's video capacities usually used for?
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A: music video

Problem: Zinc chemistry is similar to the chemistry of the late first-row transition metals nickel and copper, though it has a filled d-shell, so its compounds are diamagnetic and mostly colorless. The ionic radii of zinc and magnesium happen to be nearly identical. Because of this some of their salts have the same crystal structure and in circumstances where ionic radius is a determining factor zinc and magnesium chemistries have much in common. Otherwise there is little similarity. Zinc tends to form bonds with a greater degree of covalency and it forms much more stable complexes with N- and S- donors. Complexes of zinc are mostly 4- or 6- coordinate although 5-coordinate complexes are known.
What is the determining factor where zinc and magnesium are very similar chemically?
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Answer: ionic radius

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The Laurentian Highlands, the Interior Plains and the Interior Highlands lie between the two coasts, stretching from the Gulf of Mexico northward, far beyond the national boundary, to the Arctic Ocean. The central plains are divided by a hardly perceptible height of land into a Canadian and a United States portion. It is from the United States side, that the great Mississippi system discharges southward to the Gulf of Mexico. The upper Mississippi and some of the Ohio basin is the semi-arid prairie region, with trees originally only along the watercourses. The uplands towards the Appalachians were included in the great eastern forested area, while the western part of the plains has so dry a climate that its native plant life is scanty, and in the south it is practically barren.
What Highland stop at the national boundary?
A: unanswerable

Context and question: Evidence of infection in fossil remains is a subject of interest for paleopathologists, scientists who study occurrences of injuries and illness in extinct life forms. Signs of infection have been discovered in the bones of carnivorous dinosaurs. When present, however, these infections seem to tend to be confined to only small regions of the body. A skull attributed to the early carnivorous dinosaur Herrerasaurus ischigualastensis exhibits pit-like wounds surrounded by swollen and porous bone. The unusual texture of the bone around the wounds suggests they were afflicted by a short-lived, non-lethal infection. Scientists who studied the skull speculated that the bite marks were received in a fight with another Herrerasaurus. Other carnivorous dinosaurs with documented evidence of infection include Acrocanthosaurus, Allosaurus, Tyrannosaurus and a tyrannosaur from the Kirtland Formation. The infections from both tyrannosaurs were received by being bitten during a fight, like the Herrerasaurus specimen.
How did tyrannosaurs become infected?
Answer: being bitten during a fight

Question: Egyptian music is a rich mixture of indigenous, Mediterranean, African and Western elements. It has been an integral part of Egyptian culture since antiquity. The ancient Egyptians credited one of their gods Hathor with the invention of music, which Osiris in turn used as part of his effort to civilise the world. Egyptians used music instruments since then. Contemporary Egyptian music traces its beginnings to the creative work of people such as Abdu El Hamouli, Almaz and Mahmoud Osman, who influenced the later work of Sayed Darwish, Umm Kulthum, Mohammed Abdel Wahab and Abdel Halim Hafez whose age is considered the golden age of music in Egypt and the whole Middle East and North-Africa. Prominent contemporary Egyptian pop singers include Amr Diab and Mohamed Mounir.
Is there an answer to this question: Who is credited with invention of music by ancient Egyptians?

Answer: Hathor

Question: Most copper is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0% copper. Examples include Chuquicamata in Chile, Bingham Canyon Mine in Utah, United States and El Chino Mine in New Mexico, United States. According to the British Geological Survey, in 2005, Chile was the top mine producer of copper with at least one-third world share followed by the United States, Indonesia and Peru. Copper can also be recovered through the in-situ leach process. Several sites in the state of Arizona are considered prime candidates for this method. The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.
Is there an answer to this question: From what types of mines is copper extracted?

Answer:
open pit mines