End Of Unit Questions Flashcards Preview

GCSE Chemistry 1.7 Our Changing Planet > End Of Unit Questions > Flashcards

Flashcards in End Of Unit Questions Deck (18)
Loading flashcards...

Why should we be careful not to waste the earths resources?

They're non renewable


Name three gases that scientists think were in the early atmosphere

•carbon dioxide
•water vapour


Name 4 gases that are now in the atmosphere

•carbon dioxide
•any other noble gas


How did the oceans form?

The earth cooled and the water vapour in the atmosphere condensed to become the oceans


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


What are tectonic plates?

The earths crust and upper mantle that has been split into large slabs


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


About how much do the tectonic plates move each year?

A few cm


What happens at plate boundaries?

Earthquakes, volcanoes and tsunamis


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


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


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


Why are there so many theories about how life began?

There is no evidence to prove any individual theory


Outline the Miller-Urey experiment

Used a mixture of:
And a high voltage to stimulate lightning. This produced amino acids that formed life


What is meant by primordial soup?

A mixture of organic molecules/amino acids needed for life, in water/oceans


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


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


Name the parts of the earth, starting from its centre

•inner core
•outer core