OCR 21st Century Science: C1

What is the air made of?

78% nitrogen 21% oxygen 1% others inc CO2 and O2

Why are gas % quoted from dry air?

The amount of water vapour is variable

What is the main source of CO2 to the air?

Burning fuels

What does CO2 cause?

Global warming

What other pollutant gases are in the air (not CO2)?

Carbon monoxide, sulphur dioxide and nitrogen oxides

What pollutant does incomplete combustion cause?

Carbon particles

What are the issues with carbon particle pollution?

Dirty buildings and breathing problems

What does sulphur dioxide cause?

Acid rain

What was the early atmosphere mostly made of?

CO2 and water vapour

Where did the early atmosphere come from?

Gases released by volcanoes

Where did the oceans come from?

Water vapour from early atmosphere condensed when the temperature cooled

What 2 things happened to reduce the CO2 from the early atmosphere?

Dissolved in oceans to form sedimentary rock and trapped underground to eventually form fossil fuels

What 3 pieces of evidence are there for the early atmosphere composition?

Chemical composition of rocks, air bubbles trapped in ice and fossils

What process do fossils show that could have lowered air CO2?

Photosynthesis

Accurate

Obtaining the correct values, using accurate equipment

Reliable

Repeat data is close together

Range

Difference between smallest and largest value

Mean

Sum of values divided by number of values

Outlier

Value that is significantly different from other repeats

Real difference

Where values from data sets do not overlap