Problem: Zinc:

The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficient sacrificial anode in cathodic protection (CP). For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe. Zinc acts as the anode (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline.[note 2] Zinc is also used to cathodically protect metals that are exposed to sea water from corrosion. A zinc disc attached to a ship's iron rudder will slowly corrode, whereas the rudder stays unattacked. Other similar uses include a plug of zinc attached to a propeller or the metal protective guard for the keel of the ship.

Why does zinc harm metals exposed to sea water?
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A: unanswerable

Problem: Bras%C3%ADlia:

The major roles of construction and of services (government, communications, banking and finance, food production, entertainment, and legal services) in Brasilia's economy reflect the city's status as a governmental rather than an industrial center. Industries connected with construction, food processing, and furnishings are important, as are those associated with publishing, printing, and computer software. GDP is divided in Public Administration 54.8%, Services 28.7%, Industry 10.2%, Commerce 6.1%, Agribusiness 0.2%.

What shows the city's status as an industrial center?
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A: unanswerable

Problem: Dialect:

Italians in different regions today may also speak regional varieties of standard Italian, or regional Italian dialects, which, unlike the majority of languages of Italy, are actually dialects of standard Italian rather than separate languages. A regional Italian dialect is generally standard Italian that has been heavily influenced or mixed with local or regional native languages and accents.

The majority of Italian languages are dialects of what?
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A: unanswerable

Problem: Solar energy:

In the last two decades, photovoltaics (PV), also known as solar PV, has evolved from a pure niche market of small scale applications towards becoming a mainstream electricity source. A solar cell is a device that converts light directly into electricity using the photoelectric effect. The first solar cell was constructed by Charles Fritts in the 1880s. In 1931 a German engineer, Dr Bruno Lange, developed a photo cell using silver selenide in place of copper oxide. Although the prototype selenium cells converted less than 1% of incident light into electricity, both Ernst Werner von Siemens and James Clerk Maxwell recognized the importance of this discovery. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the crystalline silicon solar cell in 1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4.56%. By 2012 available efficiencies exceed 20% and the maximum efficiency of research photovoltaics is over 40%.

In the 1880s, who constructed the first solar cell?
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A:
Charles Fritts