Context and question: 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.
The transformation of silver to a powdery allotrope at low temperature is know as what?
Answer: unanswerable
Context and question: The city council of the city of Bern decided against having twinned cities except for a temporary (during the UEFA Euro 2008) cooperation with the Austrian city Salzburg
What did the city decide again?
Answer: having twinned cities
Context and question: New York City has over 28,000 acres (110 km2) of municipal parkland and 14 miles (23 km) of public beaches. Parks in New York City include Central Park, Prospect Park, Flushing Meadows–Corona Park, Forest Park, and Washington Square Park. The largest municipal park in the city is Pelham Bay Park with 2,700 acres (1,093 ha).
How many miles of public beach are located in New York City?
Answer:
14