Problem: Copper:

Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined and smelted has been extracted since 1900, and more than half was extracted in only the last 24 years. As with many natural resources, the total amount of copper on Earth is vast (around 1014 tons just in the top kilometer of Earth's crust, or about 5 million years' worth at the current rate of extraction). However, only a tiny fraction of these reserves is economically viable, given present-day prices and technologies. Various estimates of existing copper reserves available for mining vary from 25 years to 60 years, depending on core assumptions such as the growth rate. Recycling is a major source of copper in the modern world. Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of peak copper, analogous to peak oil.

What is a major source of cooper in modern times?
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A: Recycling


Problem: States of Germany:

Federalism is one of the entrenched constitutional principles of Germany. According to the German constitution (called Grundgesetz or in English Basic Law), some topics, such as foreign affairs and defense, are the exclusive responsibility of the federation (i.e., the federal level), while others fall under the shared authority of the states and the federation; the states retain residual legislative authority for all other areas, including "culture", which in Germany includes not only topics such as financial promotion of arts and sciences, but also most forms of education and job training. Though international relations including international treaties are primarily the responsibility of the federal level, the constituent states have certain limited powers in this area: in matters that affect them directly, the states defend their interests at the federal level through the Bundesrat (literally Federal Council, the upper house of the German Federal Parliament) and in areas where they have legislative authority they have limited powers to conclude international treaties "with the consent of the federal government".

What is the federal system is defended through?
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A: unanswerable


Problem: Buckingham Palace:

Adjacent to the palace is the Royal Mews, also designed by Nash, where the royal carriages, including the Gold State Coach, are housed. This rococo gilt coach, designed by Sir William Chambers in 1760, has painted panels by G. B. Cipriani. It was first used for the State Opening of Parliament by George III in 1762 and has been used by the monarch for every coronation since George IV. It was last used for the Golden Jubilee of Elizabeth II. Also housed in the mews are the coach horses used at royal ceremonial processions.

Who destroyed the Royal Mews?
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A: unanswerable


Problem: Hydrogen:

This reaction is favored at low pressures but is nonetheless conducted at high pressures (2.0  MPa, 20 atm or 600 inHg). This is because high-pressure H
2 is the most marketable product and Pressure Swing Adsorption (PSA) purification systems work better at higher pressures. The product mixture is known as "synthesis gas" because it is often used directly for the production of methanol and related compounds. Hydrocarbons other than methane can be used to produce synthesis gas with varying product ratios. One of the many complications to this highly optimized technology is the formation of coke or carbon:

At what pressure does PSA work best in?
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A:
high pressures