Earth and atmospheric science

Question 1

What produced the gases that formed

Earth’s early atmosphere?

Answer 1

Volcanic activity

Question 2

Describe how Earth’s early atmosphere formed

Answer 2

• Initially, the Earth’s surface was molten with no
  atmosphere.
• Cooling caused land masses to solidify.
• Volcanoes formed on the land masses and released
  gases which formed the early atmosphere.

Question 3

What was the Earth’s early atmosphere thought to

contain?

Answer 3

• Little or no oxygen.
• Large amount of carbon dioxide.
• Water vapour.
• Small amounts of other gases.

Question 4

How did oceans initially form?

Answer 4

Condensation of water vapour.

Question 5

How did the amount of carbon dioxide in the

atmosphere decrease after oceans formed?

Answer 5

Carbon dioxide dissolved into the oceans
so the amount of carbon dioxide in the
atmosphere decreased

Question 6

How did the amount of oxygen in the early Earth’s

atmosphere increase?

Answer 6

The growth of early plants used carbon dioxide
for photosynthesis and released oxygen. This
increased the amount of oxygen and decreased
the amount of carbon dioxide in the atmosphere.

Question 7

What is the chemical test for oxygen?

Answer 7

Insert a glowing splint into a test tube of
gas. If oxygen is present, the splint will
ignite.

Question 8

What are greenhouse gases?

Answer 8

Various gases in the atmosphere (such as carbon dioxide, methane and water vapour) that absorb the heat radiated from Earth.

Question 9

What is the greenhouse effect?

Answer 9

• Electromagnetic radiation from the sun passes through
  the Earth’s atmosphere.
• The Earth absorbs some radiation and warms up.
• Heat is radiated from the Earth as infrared radiation.
• Some of the infrared radiation is absorbed by
  greenhouse gases in the atmosphere which warms the
  atmosphere.

Question 10

How has human activity increased atmospheric

carbon dioxide concentration?

Answer 10

- Burning fossil fuels for energy releases carbon
dioxide.
- Deforestation reduces the amount of
photosynthesis occurring so less carbon
dioxide is converted to oxygen.

Question 11

Evaluate the evidence that human activity is causing

climate change

Answer 11

• There is a correlation between carbon dioxide
  concentration in the atmosphere, fossil fuel
  consumption and temperature change.
• Correlation doesn’t mean causation.
• There may be uncertainties in the data (e.g. location
  of the measurements and historical accuracy).

Question 12

What is the current composition of Earth’s atmosphere?

Answer 12

Nitrogen - 78%
Oxygen - 21%
Argon - 0.93%
Carbon - 0.04%

Question 13

What are the effects of global warming?

Answer 13

• Melting of polar ice caps.
• Difficulties acquiring drinking water.
• Flooding.
• Forest fires.
• Destruction of ecosystems.

Question 14

How has human activity increased the amount of methane in the atmosphere

Answer 14

• Raising livestock such as cows.

- Decay of organic waste in landfill sites.

Question 15

How can the effects of global warming be mitigated?

Answer 15

• Construct flood defences in areas of low lying
  land.
• Use of irrigation systems to provide water in
  drought.
• Produce alternative crops which are better
  adapted to the new environment