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The accumulation of water vapor, carbon dioxide, and nitrogen in Earth’s early atmosphere approximately 4 billion years ago resulted mainly from*
Earth’s early atmosphere contained carbon dioxide, sulfur dioxide, hydrogen, nitrogen, water vapor, methane, and ammonia. These gases were present in the atmosphere primarily because*
Outgassing of water vapor, carbon dioxide, and nitrogen initially formed Earth’s early*
The major source of oxygen in Earth’s Early Proterozoic atmosphere is inferred to have been produced by*
Which gas is inferred to have been absent from Earth’s atmosphere during the Early Archean Era?*
Most of the oceanic oxygen that began to enter Earth’s atmosphere in the early Proterozoic Era was probably produced by*
Scientists infer that oxygen first began to enter Earth’s atmosphere after the appearance of*
Approximately 2.2 billion years ago, which gas was first added in large amounts to Earth’s atmosphere from life-forms that evolved in the oceans?*
Scientists infer that oxygen in Earth’s atmosphere did not exist in large quantities until after*
Oxygen in Earth’s early atmosphere was first produced during the Precambrian from*
In which two Earth regions is oxygen the second most abundant element by volume?*
Base your answers to questions 12 on the geologic timeline below and on your knowledge of Earth science. The geologic timeline, drawn to scale, represents Earth’s geologic history. The letters A through H on the timeline represent the times of occurrence for specific, labeled geologic events. The time of occurrence for letter A has been omitted.
Describe the major change in Earth’s atmosphere that was occurring at the time when the first cells with a nucleus appeared on Earth. *
Base your answers to questions 13 on the data table below and on your knowledge of Earth science. The data table shows the average level of atmospheric carbon dioxide (CO2), measured in parts per million (ppm), for the month of February at the Mauna Loa observatory in Hawaii from 2008 to 2014.
These measurements of atmospheric carbon dioxide were collected at an altitude of 3.4 kilometers. Identify the temperature zone of the atmosphere where these data were collected. *
Base your answers to questions 14 on the data table below and on your knowledge of Earth science. The data table shows how the destruction of the ozone layer in Earth’s atmosphere has affected the amount of ultraviolet radiation reaching Earth’s surface beneath the areas of ozone destruction.
The ozone layer is mostly concentrated between 20 and 25 kilometers above Earth’s surface. State the name of the atmospheric temperature zone layer where this ozone concentration can be found. *
Base your answers to questions 15 on the passage and graph below and on your knowledge of Earth science. The graph shows changes in the amount of chlorofluorocarbon production, in tons per year (T/y), by some countries over a 10-year period.
CFCs and Ozone
CFCs (chlorofluorocarbons) are chemicals that threaten to destroy stratospheric ozone. CFCs were first manufactured in 1928 to be used as chilling agents in refrigerators. In later years, they were used for cleaning electrical circuit boards and to make foam for insulation. Unfortunately, scientists found that these chemicals escaped into the atmosphere and rose to the stratosphere. In the stratosphere, intense ultraviolet (UV) radiation broke the CFCs down, producing chlorine, a gas that reacts with and destroys ozone. In 1974, two scientists identified the depletion of stratospheric ozone from the release of CFCs. After this discovery, 27 countries agreed to reduce production of CFCs, because ozone in the stratosphere protects all life from the Sun’s most damaging UV rays.
Write the chemical symbol for the element produced by the breakdown of CFCs. Describe one environmental impact that results from this element being released into Earth’s stratosphere.