NAME:
DATE:
F – Block
The Earth’s Atmosphere
1. The table below shows how the composition of the Earth’s atmosphere has changed since
the formation of the Earth 4.6 billion years ago.
% Composition of atmosphere billions of
% Composition of atmosphere today
years ago
Carbon Dioxide
95%
Nitrogen
78%
Other gases
5%
Oxygen
21%
(water vapour, hydrogen, nitrogen,
Carbon Dioxide
0.004%
Others (Argon)
1%
carbon monoxide)
a. Use the information in the table to describe how the atmosphere today is different
from the atmosphere billions of years ago.
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
__________________________________________________________________ (4)
b. Explain why the amount of water vapour has decreased
_____________________________________________________________________
__________________________________________________________________ (2)
c. Explain how oxygen was introduced into the atmosphere
_____________________________________________________________________
__________________________________________________________________ (2)
d. What process has changed the percentages of nitrogen in the atmosphere?
__________________________________________________________________ (1)
e. What is the name of the gas in the upper layer of the atmosphere which filters out
harmful radiation from the sun?
__________________________________________________________________ (1)
f.
Which element is this layer composed of?
__________________________________________________________________ (1)
g. What type of harmful radiation does this layer shield the earth from?
__________________________________________________________________ (1)
h. Describe two effects of the rising oxygen levels in the atmosphere
i. ______________________________________________________________
____________________________________________________________(1)
ii. ______________________________________________________________
____________________________________________________________(1)
TOTAL
/ 16