Here is a question about this article: Matte solder is usually fused to provide a better bonding surface or stripped to bare copper. Treatments, such as benzimidazolethiol, prevent surface oxidation of bare copper. The places to which components will be mounted are typically plated, because untreated bare copper oxidizes quickly, and therefore is not readily solderable. Traditionally, any exposed copper was coated with solder by hot air solder levelling (HASL). The HASL finish prevents oxidation from the underlying copper, thereby guaranteeing a solderable surface. This solder was a tin-lead alloy, however new solder compounds are now used to achieve compliance with the RoHS directive in the EU and US, which restricts the use of lead. One of these lead-free compounds is SN100CL, made up of 99.3% tin, 0.7% copper, 0.05% nickel, and a nominal of 60ppm germanium.
What is the answer to this question: What's the process by which bare copper gets covered in solder?
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So... hot air solder levelling


Here is a question about this article: Estonia lies on the eastern shores of the Baltic Sea immediately across the Gulf of Finland from Finland on the level northwestern part of the rising East European platform between 57.3° and 59.5° N and 21.5° and 28.1° E. Average elevation reaches only 50 metres (164 ft) and the country's highest point is the Suur Munamägi in the southeast at 318 metres (1,043 ft). There is 3,794 kilometres (2,357 mi) of coastline marked by numerous bays, straits, and inlets. The number of islands and islets is estimated at some 2,355 (including those in lakes). Two of them are large enough to constitute separate counties: Saaremaa and Hiiumaa. A small, recent cluster of meteorite craters, the largest of which is called Kaali is found on Saaremaa, Estonia.
What is the answer to this question: What is the average elevation of Estonia?
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So... 50 metres (164 ft)


Here is a question about this article: The controversy surrounding affirmative action's effectiveness is based on the idea of class inequality. Opponents of racial affirmative action argue that the program actually benefits middle- and upper-class African Americans and Hispanic Americans at the expense of lower-class European Americans and Asian Americans. This argument supports the idea of class-based affirmative action. America's poor is disproportionately made up of people of color, so class-based affirmative action would disproportionately help people of color. This would eliminate the need for race-based affirmative action as well as reducing any disproportionate benefits for middle- and upper-class people of color.
What is the answer to this question: What do some people believe should be the basis for affirmative action instead of race based legislation?
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So...
class-based affirmative action