Here is a question about this article: Electrochemical migration (ECM) is the growth of conductive metal filaments on or in a printed circuit board (PCB) under the influence of a DC voltage bias. Silver, zinc, and aluminum are known to grow whiskers under the influence of an electric field. Silver also grows conducting surface paths in the presence of halide and other ions, making it a poor choice for electronics use. Tin will grow "whiskers" due to tension in the plated surface. Tin-Lead or solder plating also grows whiskers, only reduced by the percentage Tin replaced. Reflow to melt solder or tin plate to relieve surface stress lowers whisker incidence. Another coating issue is tin pest, the transformation of tin to a powdery allotrope at low temperature.
What is the answer to this question: What's the process whereby metal filaments are grown on or in a PCB via DC voltage?
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So... Electrochemical migration

Here is a question about this article: General Frossard's II Corps and Marshal Bazaine's III Corps crossed the German border on 2 August, and began to force the Prussian 40th Regiment of the 16th Infantry Division from the town of Saarbrucken with a series of direct attacks. The Chassepot rifle proved its worth against the Dreyse rifle, with French riflemen regularly outdistancing their Prussian counterparts in the skirmishing around Saarbrucken. However the Prussians resisted strongly, and the French suffered 86 casualties to the Prussian 83 casualties. Saarbrucken also proved to be a major obstacle in terms of logistics. Only one railway there led to the German hinterland but could be easily defended by a single force, and the only river systems in the region ran along the border instead of inland. While the French hailed the invasion as the first step towards the Rhineland and later Berlin, General Le Buf and Napoleon III were receiving alarming reports from foreign news sources of Prussian and Bavarian armies massing to the southeast in addition to the forces to the north and northeast.
What is the answer to this question: On which date did Frossard's and Bazaines's troops cross the German border?
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So... 2 August

Here is a question about this article: Hyderabad produces around 4,500 tonnes of solid waste daily, which is transported from collection units in Imlibun, Yousufguda and Lower Tank Bund to the dumpsite in Jawaharnagar. Disposal is managed by the Integrated Solid Waste Management project which was started by the GHMC in 2010. Rapid urbanisation and increased economic activity has also led to increased industrial waste, air, noise and water pollution, which is regulated by the Telangana Pollution Control Board (TPCB). The contribution of different sources to air pollution in 2006 was: 2050% from vehicles, 4070% from a combination of vehicle discharge and road dust, 1030% from industrial discharges and 310% from the burning of household rubbish. Deaths resulting from atmospheric particulate matter are estimated at 1,7003,000 each year. Ground water around Hyderabad, which has a hardness of up to 1000 ppm, around three times higher than is desirable, is the main source of drinking water but the increasing population and consequent increase in demand has led to a decline in not only ground water but also river and lake levels. This shortage is further exacerbated by inadequately treated effluent discharged from industrial treatment plants polluting the water sources of the city.
What is the answer to this question: What is the rating for the hardness of Hyderabad's water?
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So...
1000 ppm