Context and question: New Haven lies in the transition between a humid continental climate (Köppen climate classification: Dfa) and humid subtropical climate (Köppen Cfa), but having more characteristics of the former, as is typical of much of the New York metropolitan area. Summers are humid and warm, with temperatures exceeding 90 °F (32 °C) on 7–8 days per year. Winters are cold with moderate snowfall interspersed with rainfall and occasionally mixed precipitation. The weather patterns that affect New Haven result from a primarily offshore direction, thus reducing the marine influence of Long Island Sound—although, like other marine areas, differences in temperature between areas right along the coastline and areas a mile or two inland can be large at times.
New Haven's climate is largely analogous to what major adjoining metropolitan area?
Answer: New York
Context and question: The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2) and to a lesser extent chalcocite (Cu2S). These minerals are concentrated from crushed ores to the level of 10–15% copper by froth flotation or bioleaching. Heating this material with silica in flash smelting removes much of the iron as slag. The process exploits the greater ease of converting iron sulfides into its oxides, which in turn react with the silica to form the silicate slag, which floats on top of the heated mass. The resulting copper matte consisting of Cu2S is then roasted to convert all sulfides into oxides:
What happens to the silicate slag  during the flash smelting process?
Answer: floats on top
Context and question: Maximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dynamic output impedance of the transmitter as analyzed as a source impedance but rather the design value (typically 50 ohms) required for efficient and safe operation of the transmitting circuitry. The intended impedance is normally resistive but a transmitter (and some receivers) may have additional adjustments to cancel a certain amount of reactance in order to "tweak" the match. When a transmission line is used in between the antenna and the transmitter (or receiver) one generally would like an antenna system whose impedance is resistive and near the characteristic impedance of that transmission line in order to minimize the standing wave ratio (SWR) and the increase in transmission line losses it entails, in addition to supplying a good match at the transmitter or receiver itself.
What requires matching of the empedance to an antenna system?
Answer:
Maximum power transfer