Problem: Like aluminium, copper is 100% recyclable without any loss of quality, regardless of whether it is in a raw state or contained in a manufactured product. In volume, copper is the third most recycled metal after iron and aluminium. It is estimated that 80% of the copper ever mined is still in use today. According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of copper in use in society is 3555 kg. Much of this is in more-developed countries (140300 kg per capita) rather than less-developed countries (3040 kg per capita).
What other metal besides copper is 100% recyclable?
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Answer: aluminium

Problem: In 1950, whites represented 94.7% of Boston's population. From the 1950s to the end of the 20th century, the proportion of non-Hispanic whites in the city declined; in 2000, non-Hispanic whites made up 49.5% of the city's population, making the city majority-minority for the first time. However, in recent years the city has experienced significant gentrification, in which affluent whites have moved into formerly non-white areas. In 2006, the US Census Bureau estimated that non-Hispanic whites again formed a slight majority. But as of 2010, in part due to the housing crash, as well as increased efforts to make more affordable housing more available, the minority population has rebounded. This may also have to do with an increased Latino population and more clarity surrounding US Census statistics, which indicate a Non-Hispanic White population of 47 percent (some reports give slightly lower figures).
In recent years, the whote population has begun to move where?
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Answer: formerly non-white areas

Problem: According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 and half of all energy needs with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".
Photovoltaic and solar-thermal plants will never meet most of the world's demand for electricity by what year?
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Answer:
unanswerable