The C-14 in an organism begins to decay when it dies

试卷相关题目

• 1Radiocarbon is reliable in dating an object back to at least 50，000 years.

  A.Right

  B.Wrong

  C.Not mentioned

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• 2Radar is used to determine the characteristics of radiocarbon

  A.Right

  B.Wrong

  C.Not mentioned

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• 3An atom of ordinary carbon has six protons and eight neutrons

  A.Right

  B.Wrong

  C.Not mentioned

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• 4The radiocarbon dating technique is only about 40 years old

  A.Right

  B.Wrong

  C.Not mentioned

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• 5Nowadays many scientists depend on radiocarbon for dating age-old objects

  A.Right

  B.Wrong

  C.Not mentioned

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• 6The half-life of C-14 is about 25，000 years.

  A.Right

  B.Wrong

  C.Not mentioned

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• 7Liquid water only exists

  A.in the center of the earth.

  B.on the surface of our planet.

  C.in a very narrow range of temperatures.

  D.in the coastal areas of the earth.

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• 8The total quantity of water on Earth

  A.remains almost unchanged.

  B.has greatly increased in recent years.

  C.is decreasing constantly.

  D.is affected by global warming.

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• 9Most of the fresh water on Earth

  A.is stored underground.

  B.is in the form of ice at the Poles and on mountains.

  C.is found in rivers and lakes.

  D.comes from the rain.

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• 10The word “fraction” in the second paragraph means

  A.a very small amount.

  B.a large area.

  C.an important system.

  D.a major source of information

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