Atmosphere

Question 1

Gases in the early atmosphere

Answer 1

Carbon dioxide and water vapour

Question 2

How the present-day atmosphere developed

Answer 2

1. Evolution of respiring plants and animals
2. Volcanic activity
3. Cooling down of planet and condensation of water vapour to form oceans
4. Evolution of photosynthesising bacteria and algae

Question 3

Composition of the present day atmosphere including % of the 4 main gases

Answer 3

Nitrogen 78%, Oxygen 21%, Argon 0.9%, Carbon Dioxide 0.04%

Question 4

Properties and uses of gases in the air

Answer 4

Nitrogen- Important plant nutrient, used to make fertilisers
Oxygen - Reactant in respiration, used for life support and other medical uses
Carbon dioxide - starves fire of oxygen, used in fire extinguishers
Helium - Less dense than air, used to fill balloons
Neon - Glows, used for advertising signs
Argon - Inert (unreactive), used to fill light bulbs

Question 5

Fractional distillation to separate gases in the air

Answer 5

A way to separate liquids based on their boiling temperature.