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?

   • Volcanoes made oxygen, which built up at once
   • A dimmer Sun froze the oceans solid, and the ice released oxygen
   • Cyanobacteria made it, it reacted away at first, then built up
   • Photosynthesis took in oxygen and released carbon dioxide
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
   • Today's oceans being salty
   • Volcanoes giving off oxygen
   • Ancient zircons show solid crust very early

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)?

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

   Luz's friend says early Earth's air was just like today's, with plenty of oxygen. Which response is best (Smithsonian)?

   • Disagree: it had almost no oxygen until about 2.4 billion years ago
   • Agree: volcanoes gave it oxygen
   • Agree: air has stayed at 21% oxygen
   • Disagree: it had more oxygen than today
6. 5.

   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: lava releases oxygen
   • Agree: volcanoes are full of oxygen

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 1.7 times
   • About 35 times
   • About 14 times
   • About 0.6 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 12:30 a.m., near the start
   • About 11:30 a.m.
   • About 2:24 a.m.
   • About 11:59 p.m., near the end
10. 8.

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

    • Yes: the Sun makes water
    • No: oxygen gas in the air is what made the ocean water
    • Yes: volcanic water vapor could still condense
    • No: ocean water came from space alone
11. 9.

    An oxygen bar rising over time, with living things using oxygen. Why does the rise in oxygen matter for living things today, by Ari's reading (Smithsonian)?

    • Living things like us make oxygen when we breathe out
    • Oxygen was here for them from the start
    • Volcanoes still make our oxygen
    • Oxygen-using life grew out of the oxygen rise
12. 10.

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

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