Week 4

Question 1

What % of the earths atmosphere is nitrogen?

Answer 1

80%

Question 2

What % of the earths atmosphere is oxygen?

Answer 2

20%

Question 3

What are the gases are in the earths atmosphere other than nitrogen and oxygen?

Answer 3

Carbon dioxide, water vapour, noble gases

Question 4

When was the Earth formed?

Answer 4

4 .6 billion years ago

Question 5

What is the lead to be the composition of the earths atmosphere at the start of its existence?

Answer 5

It’s believed to have contained mostly carbon dioxide and little or no oxygen ( similar to Mars and Venus)

Question 6

What is believed to be the source of nitrogen and water vapour in the earth atmosphere?

Answer 6

Volcanoes

Question 7

What happened to the water vapour produced by volcanoes overtime?

Answer 7

The water vapour condensed to form oceans

Question 8

What causes the oxygen levels in the Earth atmosphere to increase over time?

Answer 8

• algae and plants evolved
• Algae plants photosynthesise and produce oxygen

Question 9

What caused the carbon dioxide levels to decrease overtime?

Answer 9

1. • water vapour condensed to form oceans
   • Carbon dioxide dissolved in the oceans
2. • algae and plants evolve and began photosynthesis which takes in carbon dioxide
3. • carbon dioxide can become “locked up” in sedimentary rocks

Question 10

Explain how greenhouse gases lead to an increase in the earths temperature

Answer 10

• greenhouse gases allow shorter wavelength, radiation to pass through the atmosphere from the sun
• The Earth absorbs the short length radiation and remit it as long wave radiation
• the long wave radiation is absorbed by the greenhouse gases

Question 11

What are some human activities that contribute to greenhouse gases?

Answer 11

• driving and consuming electricity leads to an increase in carbon dioxide
• Raising livestock (cows) contributes to methane
• The decay of organic waste in landfill sites contributes to methane levels

Question 12

What are the main two greenhouse gases?

Answer 12

Carbon dioxide and methane

Question 13

What is meant by carbon footprint?

Answer 13

The total amount of carbon dioxide and other greenhouse gases omitted over the life-cycle of a product

Question 14

How can the carbon footprint of a product be reduced?

Answer 14

• Using less electricity
• reducing the amount of travel or transportation of a product