Earth's early air and oceans

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Four chain cards, labeled A to D. Which chain best explains the rise of oxygen, by Esme's reading?

   • Photosynthesis took in oxygen and released carbon dioxide
   • A dimmer Sun froze the oceans solid, and the ice released oxygen
   • Cyanobacteria made it, it reacted away at first, then built up
   • Volcanoes made oxygen, which built up at once
2. 2.

   Four evidence cards, labeled A to D. Which evidence suggests liquid water was present very early, by Jun's reading?

   • Oxygen gas found in the earliest air, as today
   • Ancient zircons show solid crust very early
   • Today's oceans being salty
   • Volcanoes giving off oxygen

3. Read this first

   Oxygen in the air over time (Smithsonian, NASA)

   Time	Oxygen in the air
   before about 2.7 billion years ago	almost none
   about 2.4 billion years ago	first fills the air (NASA)
   about 600 million years ago	about one-fifth of today's level
   today	21%

4. 3.

   Why was the Great Oxidation Event one of the biggest changes to Earth's surface, by Kira's reading (NASA)?

   • Oxygen filled the air and oceans for the first time
   • It made the first volcanoes
   • It happened in a single year
   • It removed the oxygen that had been in the air and oceans
5. 4.

   a volcano giving off gas; cyanobacteria giving off oxygen. Milo's cousin says volcanoes put the oxygen into the air. Which response is best?

   • Disagree: oxygen came from the Moon
   • Disagree: volcanoes gave carbon dioxide; photosynthesis made the oxygen
   • Agree: volcanoes are full of oxygen
   • Agree: lava releases oxygen
6. 5.

   Noah's friend says a dimmer young Sun means Earth must have been frozen for its first billions of years. Which response is best (Smithsonian)?

   • Disagree: greenhouse gases kept Earth above freezing
   • Disagree: the young Sun was brighter
   • Agree: a dimmer Sun means a frozen, icy Earth for billions of years
   • Agree: Earth had no air to trap heat

7. Oxygen in the air (Smithsonian)

   Time	Oxygen
   about 350 million years ago	20%
   about 300 million years ago	up to 35%
   today	21%

8. 6.

   Smithsonian: oxygen was about 20% of the air 350 million years ago and rose to as much as 35%. About how many times today's 21% was that peak, by Pia's math?

   • About 35 times
   • About 0.6 times
   • About 1.7 times
   • About 14 times
9. 7.

   4.6 billion years = 24 hours, starting at midnight. On a 24-hour clock for Earth's 4.6 billion years, about what time of day would the Great Oxidation Event (2.4 billion years ago) fall, by Ren's math?

   • About 2:24 a.m.
   • About 11:30 a.m.
   • About 12:30 a.m., near the start
   • About 11:59 p.m., near the end
10. 8.

    Four model cards, labeled A to D. Which model supports the idea that life changed Earth's air, by Tala's reading?

    • Oxygen rises after photosynthesizers appear, then redbeds form
    • Oxygen rises each time volcanoes erupt
    • Oxygen rises before any life appears
    • Carbon dioxide rises as photosynthesizers spread and oxygen falls
11. 9.

    If no icy bodies had ever hit Earth, could there still be oceans, by Zee's reading?

    • No: oxygen gas in the air is what made the ocean water
    • Yes: the Sun makes water
    • No: ocean water came from space alone
    • Yes: volcanic water vapor could still condense
12. 10.

    Four order cards, labeled A to D. Which order of events fits Earth's early history, by Bo's reading?

    • Volcanic air, oceans, cyanobacteria, then the oxygen rise
    • Oxygen rise, then cyanobacteria
    • Oxygen air, then volcanoes, then oceans
    • Cyanobacteria, then oceans, then volcanic air