Early and today's atmosphere

Question 1

How was the early atmosphere formed?

Answer 1

Gases that escaped from volcanoes

Question 2

What were the main gases in the early atmosphere?

Answer 2

Carbon dioxide and water vapour (they still exist today)

Question 3

What is one of the most reactive gases in the atmosphere?

Answer 3

Oxygen

Question 4

What is an example of an oxidation reaction?

Answer 4

Rusting metals and the maintenance of fire

Question 5

What is the evidence for increasing oxygen levels in the atmosphere?

Answer 5

Recent rocks contain iron that is oxidised, older rocks do not

Question 6

What was the dissolved carbon dioxide in the oceans used for?

Answer 6

Early sea plants used it for photosynthesis and some sea animals used it to make their shells

Question 7

What holds the molecules of water together?

Answer 7

Intermolecular forces

Question 8

What did photosynthesis do to the levels of carbon dioxide and oxygen levels in the atmosphere?

Answer 8

It decreased the levels of carbon dioxide and increased the levels of oxygen

Question 9

What does the modern atmosphere contain?

Answer 9

78% nitrogen,
21% oxygen,
1% argon,
0.03% carbon dioxide
and tiny amounts of other gases

Question 10

What method is used to separate the gases in the air?

Answer 10

Fractional distillation

Question 11

What causes the gases in the atmosphere to change?

Answer 11

Erupting volcanoes, humans burning fossil fuels and forests being cut down

Question 12

In a chemical reaction, can atoms be created or destroyed?

Answer 12

NO

Question 13

How do you balance a formulae equation?

Answer 13

Change the coefficients