Input: Read this: The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2) and to a lesser extent chalcocite (Cu2S). These minerals are concentrated from crushed ores to the level of 1015% copper by froth flotation or bioleaching. Heating this material with silica in flash smelting removes much of the iron as slag. The process exploits the greater ease of converting iron sulfides into its oxides, which in turn react with the silica to form the silicate slag, which floats on top of the heated mass. The resulting copper matte consisting of Cu2S is then roasted to convert all sulfides into oxides:
Question: What does freezing copper ore materials with silica remove?

Output: unanswerable

QUES: Russian ( , russkiy yazyk, pronounced [ruskj jzk] ( listen)) is an East Slavic language and an official language in Russia, Belarus, Kazakhstan, Kyrgyzstan and many minor or unrecognised territories. It is an unofficial but widely-spoken language in Ukraine, Latvia, Estonia, and to a lesser extent, the other countries that were once constituent republics of the Soviet Union and former participants of the Eastern Bloc. Russian belongs to the family of Indo-European languages and is one of the three living members of the East Slavic languages. Written examples of Old East Slavonic are attested from the 10th century onwards.

Where is Russian popular but not an official language?
What is the answer?
ANS: Ukraine, Latvia, Estonia

QUES: Tito was the chief architect of the second Yugoslavia, a socialist federation that lasted from 1943 to 199192. Despite being one of the founders of Cominform, soon he became the first Cominform member to defy Soviet hegemony and the only one to manage to leave Cominform and begin with its own socialist program. Tito was a backer of independent roads to socialism (sometimes referred to as "national communism"). In 1951 he implemented a self-management system that differentiated Yugoslavia from other socialist countries. A turn towards a model of market socialism brought economic expansion in the 1950s and 1960s and a decline during the 1970s. His internal policies included the suppression of nationalist sentiment and the promotion of the "brotherhood and unity" of the six Yugoslav nations. After Tito's death in 1980, tensions between the Yugoslav republics emerged and in 1991 the country disintegrated and went into a series of wars and unrest that lasted the rest of the decade, and which continue to impact most of the former Yugoslav republics. He remains a very controversial figure in the Balkans.
When did the second Yugoslavia start?

ANS: 1943

Americans with Sub-Saharan African ancestry for historical reasons: slavery, partus sequitur ventrem, one-eighth law, the one-drop rule of 20th-century legislation, have frequently been classified as black (historically) or African American, even if they have significant European American or Native American ancestry. As slavery became a racial caste, those who were enslaved and others of any African ancestry were classified by what is termed "hypodescent" according to the lower status ethnic group. Many of majority European ancestry and appearance "married white" and assimilated into white society for its social and economic advantages, such as generations of families identified as Melungeons, now generally classified as white but demonstrated genetically to be of European and sub-Saharan African ancestry.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What were slaves and others of African ancestry classified by what term?
Ah, so.. hypodescent

Question: Large masses, such as ice sheets or glaciers, can depress the crust of the Earth into the mantle. The depression usually totals a third of the ice sheet or glacier's thickness. After the ice sheet or glacier melts, the mantle begins to flow back to its original position, pushing the crust back up. This post-glacial rebound, which proceeds very slowly after the melting of the ice sheet or glacier, is currently occurring in measurable amounts in Scandinavia and the Great Lakes region of North America.
Try to answer this question if possible: Where has post-glacial rebound stopped occuring?
Answer: unanswerable

Context and question: In nature, uranium is found as uranium-238 (99.2742%) and uranium-235 (0.7204%). Isotope separation concentrates (enriches) the fissionable uranium-235 for nuclear weapons and most nuclear power plants, except for gas cooled reactors and pressurised heavy water reactors. Most neutrons released by a fissioning atom of uranium-235 must impact other uranium-235 atoms to sustain the nuclear chain reaction. The concentration and amount of uranium-235 needed to achieve this is called a 'critical mass'.
What is the most prevalent unnatural isotope of uranium?
Answer:
unanswerable