Flashcards in End Of Unit Questions Deck (18)
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1
Why should we be careful not to waste the earths resources?
They're non renewable
2
Name three gases that scientists think were in the early atmosphere
•carbon dioxide
•water vapour
•nitrogen
•ammonia
•methane
•hydrogen
3
Name 4 gases that are now in the atmosphere
•nitrogen
•oxygen
•carbon dioxide
•methane
•argon
•any other noble gas
4
How did the oceans form?
The earth cooled and the water vapour in the atmosphere condensed to become the oceans
5
What was the effect of algae and plants on the early atmosphere?
They absorbed all of the carbon dioxide released from volcanic eruptions and released oxygen
6
What are tectonic plates?
The earths crust and upper mantle that has been split into large slabs
7
Why do tectonic plates move?
The mantle below them is flowing due to convection currents from radioactive decay of the core which causes the crust to move
8
About how much do the tectonic plates move each year?
A few cm
9
What happens at plate boundaries?
Earthquakes, volcanoes and tsunamis
10
Why have the amounts of gases in the atmosphere been almost the same for the last 200 million years?
Various natural processes that move carbon into and out of the atmosphere have reached a balance
11
What has been the main cause of a change in the carbon balance in the atmosphere in recent years?
The large amounts of fossil fuels that we burn
12
Why were Wegener's ideas not accepted until the 1960's?
He couldn't explain why the tectonic plates moved to cause continental drift and it wasn't until the 60's when evidence could prove it
13
Why are there so many theories about how life began?
There is no evidence to prove any individual theory
14
Outline the Miller-Urey experiment
Used a mixture of:
•water
•ammonia
•methane
•hydrogen
And a high voltage to stimulate lightning. This produced amino acids that formed life
15
What is meant by primordial soup?
A mixture of organic molecules/amino acids needed for life, in water/oceans
16
Why is the fractional distillation of liquid air done commercially?
To separate air into individual gases, to produce liquid nitrogen and oxygen which have commercial uses
17
Explain how the fractional distillation of liquid air is done
•air is cooled until it becomes liquid
•put into a fractionating column
•nitrogen boils at the lowest temperature so is collected as a gas at the top of the column
•oxygen remains as a liquid with argon and is collected at the bottom of the column
18
