1) What is the approximate percentage
of oxygen in Earth’s modern day
atmosphere?
.
Answer
21 %
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M. Rahman
2) Which gas has the largest
percentage in Earth’s modern day
atmosphere?
Answer
Nitrogen
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M. Rahman
3) Which gas made up the majority of the
Earth’s early atmosphere?
Answer
Carbon dioxide
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M. Rahman
4) Where is much of the gas that
once made up the Earth’s early
atmosphere now located?
Answer.
It dissolved in oceans and was then taken up by
marine organisms.
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M. Rahman
5) What is the approximate
percentage of carbon dioxide
currently found in the atmosphere?
Answer.
0.04 %
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M. Rahman
6) Give three ways humans have
contributed to the amount of CO2
in the atmosphere
Answer
a) deforestation
b) burning fossil fuels
c) farming
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M. Rahman
7) Which of the following activities is not a human
activity that causes small changes to the
atmosphere over time?
a)
b)
c)
d)
deforestation
burning fossil fuels
volcanoes erupting
farming
Answer
C) volcanoes erupting
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M. Rahman
8) Which process was responsible for
increasing the amount of oxygen in the
atmosphere over time?
Answer
photosynthesis
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M. Rahman
9) Which gas do plants take out of the
atmosphere?
carbon dioxide
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M. Rahman
10) Which of the following gases are released
by volcanoes?
a)
b)
c)
d)
oxygen and nitrogen
carbon dioxide and hydrogen
oxygen only
carbon dioxide and steam
Answer
d)
carbon dioxide and steam
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M. Rahman
11) Which of the following gases could be
released when fossil fuels are burned?
a)
b)
c)
d)
carbon dioxide and carbon monoxide
carbon dioxide and oxygen
ammonia and nitrogen
nitrogen and oxygen
Answer
a) carbon dioxide and carbon monoxide
C1 TOPIC 1
M. Rahman
12) How where oceans formed (3)
Answer
1) Water vapour released from volcanoes
2)Water vapour condensed as the earth cooled.
3) Rain falls to fill up the hollows in the crust.
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M. Rahman
13) Describe why burning fossil is harmful
to the earth and its environment (2).
Answer
• Increases amount of CO2 in the atmosphere,;
• carbon dioxide is a green house gas, which causes global warming;
• greenhouse gases prevent heat from leaving the earths
atmosphere;
• Trapped heat causes the earth temperature to rise.
.
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M. Rahman
14) Billions of years ago, which gas was in
the greatest amount?
Answer
Carbon dioxide
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M. Rahman
15) Give the origins of one piece of
evidence that scientist have collected
to explain the composition of the
earths atmosphere
Answer
• Antarctic ice cores-difference layers contain different
amount of each gas. Each layer represents a different time.
or
• Oxygen locked in rocks.
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M. Rahman
16) In todays atmosphere, which gas is
present that was either in very small
amounts or not at all
Answer
Oxygen
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M. Rahman
17) Explain how the levels of oxygen has
changed over billions of years (2).
Answer
Primitive green plants evolved using carbon
dioxide (1)
and released oxygen by photosynthesis (1).
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M. Rahman
18) Describe how carbon gets locked into
sedimentary rocks (2).
Answer
Carbon dioxide dissolved in sea water reacts
with other chemicals to form calcium carbonate
and calcium hydrogen carbonate (1).
The shells of dead sea creatures accumulate and
are transformed into sedimentary rocks (1)
.
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M. Rahman
19) Describe how the levels of carbon
dioxide in the atmosphere in the earths
early atmosphere was reduced(2).
Answer
By photosynthesis (1) and by dissolving in the
oceans (1)
.
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M. Rahman
20) Name three ways humans are
changing the atmosphere.
Answer
1) Burning of fossil fuels
2) deforestation
3) livestock farming
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M. Rahman
21)
iron
100 mm
79 mm
1) Explain how the above experiment could be used to determine the amount
of oxygen in the atmosphere (4 marks)
Answer
• Iron reacts with oxygen to from iron oxide.
• Reaction uses up oxygen and total amount of air
reduces.
• The water rises inside the tube to
• fill up the gap
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M. Rahman
20)
22)
iron
300 mm
? mm
1) If the atmosphere contains 21 % oxygen, what will the final reading be.
Show your working out. (3 marks)
Answer
300 x 0.21=63 mm (1)
300-63= 237mm (2)
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M. Rahman
20)
23)
iron
750 mm
592 mm
1) Show that the percentage of oxygen in the atmosphere is 21 %.
Answer
750-592 =158 (1)
158/750= 0.21 (1)
0.21 x 100 = 21 %
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M. Rahman
24)
1) Explain how the above experiment could be used to determine the
amount of oxygen in the atmosphere (4 marks)
Answer
• Copper reacts with oxygen to from copper oxide.
• Reaction uses up oxygen and total amount of air reduces.
• The gap between the syringes should reduce.
• Compare reading before heating with after heating.
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M. Rahman
25)
Iron reacts with oxygen to produce
iron oxide. Write the word equations.
Answer
Iron + Oxygen ---- Iron Oxide
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M. Rahman