Problem: Nutrition:

Dietary minerals are inorganic chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen that are present in nearly all organic molecules. The term "mineral" is archaic, since the intent is to describe simply the less common elements in the diet. Some are heavier than the four just mentioned, including several metals, which often occur as ions in the body. Some dietitians recommend that these be supplied from foods in which they occur naturally, or at least as complex compounds, or sometimes even from natural inorganic sources (such as calcium carbonate from ground oyster shells). Some minerals are absorbed much more readily in the ionic forms found in such sources. On the other hand, minerals are often artificially added to the diet as supplements; the most famous is likely iodine in iodized salt which prevents goiter.

What is the most famous mineral that is artificially added that prevents goiter?
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A: iodine

Problem: Philosophy of space and time:

But in statistical mechanics things get more complicated. On one hand, statistical mechanics is far superior to classical thermodynamics, in that thermodynamic behavior, such as glass breaking, can be explained by the fundamental laws of physics paired with a statistical postulate. But statistical mechanics, unlike classical thermodynamics, is time-reversal symmetric. The second law of thermodynamics, as it arises in statistical mechanics, merely states that it is overwhelmingly likely that net entropy will increase, but it is not an absolute law.

What are superior to classical thermodynamics?
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A: statistical mechanics

Problem: Republic of the Congo:

The current administration presides over an uneasy internal peace and faces difficult economic problems of stimulating recovery and reducing poverty, despite record-high oil prices since 2003. Natural gas and diamonds are also recent major Congolese exports, although Congo was excluded from the Kimberley Process in 2004 amid allegations that most of its diamond exports were in fact being smuggled out of the neighboring Democratic Republic of Congo; it was re-admitted to the group in 2007.

What two exports has the Congo begun producing recently?
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A: Natural gas and diamonds

Problem: Geography of the United States:

By total area (water as well as land), the United States is either slightly larger or smaller than the People's Republic of China, making it the world's third or fourth largest country. China and the United States are smaller than Russia and Canada in total area, but are larger than Brazil. By land area only (exclusive of waters), the United States is the world's third largest country, after Russia and China, with Canada in fourth. Whether the US or China is the third largest country by total area depends on two factors: (1) The validity of China's claim on Aksai Chin and Trans-Karakoram Tract. Both these territories are also claimed by India, so are not counted; and (2) How US calculates its own surface area. Since the initial publishing of the World Factbook, the CIA has updated the total area of United States a number of times.

Since the initial publication of the world factbook Guinness has done what?
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A:
unanswerable