Atmosphere

Question 1

how old is Earth?

Answer 1

4.6 billion years old, molten rock covered with volcanoes

Question 2

volcano theory

Answer 2

released water vapour and carbon dioxide, water condensed as Earth cooled, forming oceans

Question 3

comet theory

Answer 3

icy comets melted, adding to water supply

Question 4

early atmosphere

Answer 4

mostly carbon dioxide, small presence of ammonia and methane and nitrogen

Question 5

when did life first evolve?

Answer 5

3.4 billion years ago

Question 6

when did algae and bacteria first evolve?

Answer 6

2.7 billion years ago, photosynthesising, increasing oxygen levels and decreasing carbon dioxide levels in the atmosphere

Question 7

carbon ‘locked into’ rock

Answer 7

animal ate plants, using carbon in glucose as material for skeletons and skulls, died, covered with layers of fine sediment

Question 8

how did fossil fuels form?

Answer 8

skeletons and shells of animals were crushed and heated due to large scale movements

Question 9

coal

Answer 9

fossil fuel, sedimentary rock, thick plant material deposits compressed over time with no oxygen

Question 10

natural gas/ crude oil

Answer 10

deposits of plankton covered by layers of sedimentary rock, gas/ oil trapped beneath

Question 11

oceans acting as carbon sinks

Answer 11

carbon dissolves in water, reacts with metal oxides producing insoluble carbonate compounds, fell to sea bed forming carbonate rock

Question 12

why has nitrogen built up in the atmosphere?

Answer 12

unreactive

Question 13

how was ammonia and methane, produced by volcanoes, removed from the atmosphere?

Answer 13

reacted with oxygen