C13 - The Earth's Atmosphere

Question 1

What are the main gases in our atmosphere?

Answer 1

nitrogen, oxygen, carbon dioxide, argon & water vapour

Question 2

What percentage is our atmosphere made up of nitrogen? And oxygen?
What about other gases?

Answer 2

N - 78%
O - 21%
others- 1%

Question 3

Which planet do scientists believe has an atmosphere like the early atmosphere of the earth? Why?

Answer 3

mars - mainly made up CO2

Question 4

What do scientists believe formed the Earth’s early atmosphere?

Answer 4

gases - volcanoes

Question 5

What gases did volcanoes produce when the atmosphere was first formed?

Answer 5

ntrgn, CO2,wtr vpr, mthn & ammn

Question 6

What gas is thought to have condensed to form the Earth’s oceans?

Answer 6

wtr vpr

Question 7

How long ago was the earth formed?

Answer 7

4.6 billion years ago

Question 8

What happened after wtr vpr condensed to form the Earth’s oceans?

Answer 8

• CO2 dslvd. in -> weak acid
• reactd. with minerals -> precipitates
• fmd sedmts. carbnt rock on sea bed

Question 9

What was carbon dioxide also used to form in the sea? How did this help remove carbon dioxide from the atmosphere?

Answer 9

coral & mussels - died & fmd limestone = rmvl CO2

Question 10

What was formed 2.7 billion years ago, in the oceans? What did this produce?

Answer 10

phtsynthtc algae (cyanobacteria) - O2

Question 11

How do fossil fuels decrease levels of carbon dioxide?

Answer 11

carbon trapped - ↓ CO2

Question 12

Why did nitrogen gradually build up in the atmosphere?

Answer 12

unreactive

Question 13

How did the oceans cause CO2 levels to decrease?

Answer 13

dissolved

Question 14

How did oil cause CO2 levels to decrease?

Answer 14

• crude oil & natural gas fmd frm plankton
• covrd by sdmnt & bcme layers rck
• oil trppd by layers rck