C9

Question 1

Describe the Earth’s atmosphere

Answer 1

• approx 80% nitrogen
• 20% oxygen
• small proportions of other gases e.g. carbon dioxide, water vapour and noble gases

Question 2

What was the early atmosphere like?

Answer 2

there was intense volcanic activity which released gases that formed the early atmosphere

The water vapour condensed to form the oceans

Volcanoes also produced nitrogen which gradually built up in the atmosphere

When oceans formed, carbon dioxide dissolved in the water and carbonated were precipitated producing sediments

Question 3

How did oxygen increase?

Answer 3

Algae and plants produced the oxygen by photosynthesis

Question 4

How did carbon dioxide decrease?

Answer 4

• algae and plants used some of the carbon dioxide in photosynthesis
• CO₂ decreased by the formation of sedimentary rocks & fossil fuels that contain carbon

Question 5

What is the role of the greenhouse gases?

Answer 5

greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life (they absorb heat radiated from the earth, then release energy in all directions)

• water vapour, carbon dioxide and methane are all examples

Question 6

Give human activities that increase the amount of carbon dioxide and methane

Answer 6

• Cattle farming
• burning fossil fuels
• farming rice (in paddy fields)
• deforestation

Question 7

Give four potential effects of global warming and climate change

Answer 7

• rising sea levels
• glaciers and polar ice melting
• habitats changing
• changing rainfall patterns → floods or droughts

Question 8

What is the carbon footprint?

Answer 8

the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event

Question 9

How can the carbon footprint be reduced?

Answer 9

reducing emissions of carbon dioxide and methane

Question 10

What is the main source of atmospheric pollutants?

Answer 10

the combustion of fuels

Question 11

Give examples of gases that may be released into the atmosphere when a fuel is burned

Answer 11

• carbon dioxide
• water vapour
• carbon monoxide
• sulfur dioxide
• oxides of nitrogen

Question 12

What else may be released other than gases that are released into the atmosphere when a fuel is burned?

Answer 12

solid particles and unburned hydrocarbons may be released that form particulates

Question 13

Give properties of carbon monoxide

Answer 13

• it is a toxic gas,
• it is colourless and odourless
• it’s not easily detected

Question 14

Give properties/effects of sulfur dioxide

Answer 14

• cause respiratory problems in humans
• cause acid rain

Question 15

Give properties/effects of particulates

Answer 15

• cause global dimming
• cause health problems for humans