Formation of Earth's Atmosphere Practice Questions

Name the gas that makes up about four-fifths of the Earth's atmosphere.

Give the approximate percentage of oxygen in the Earth's atmosphere today.

Name two other gases that are present in the Earth's atmosphere today in small proportions.

One theory suggests that the early atmosphere was mainly one gas.

Name this gas.

Volcanoes also released a substance which later condensed to form the oceans.

Name this substance.

Name two other gases that volcanoes may have released into the early atmosphere.

Complete the word equation for photosynthesis.

carbon dioxide + water $\rightarrow$ __________ + __________

Balance the symbol equation for photosynthesis.

$\ldots\mathrm{CO_2} + \ldots\mathrm{H_2O} \rightarrow \mathrm{C_6H_{12}O_6} + \ldots\mathrm{O_2}$

Name the type of organism that first produced oxygen, about 2.7 billion years ago.

Explain how the oceans formed.

Explain two ways in which the formation of the oceans reduced the amount of carbon dioxide in the atmosphere.

Deposits of limestone are found in many parts of the world.

Describe how deposits of limestone were formed.

Describe the change in the percentage of carbon dioxide in the atmosphere shown in Figure 1.

Use Figure 1 to calculate how many times greater the percentage of carbon dioxide was 4 billion years ago than it is today.

Carbon dioxide dissolving in the oceans was one reason for the decrease shown in Figure 1.

Give two other processes that decreased the percentage of carbon dioxide in the atmosphere.

Describe how deposits of crude oil and natural gas were formed.

Explain how the formation of fossil fuels affected the percentage of carbon dioxide in the Earth's atmosphere.

Calculate the volume of oxygen in a $250\ \mathrm{cm^3}$ sample of this dry air.

Calculate the ratio of nitrogen to oxygen in this sample of dry air.

Give your answer in the form $n : 1$ to 2 significant figures.

Argon is a noble gas.

Name one other noble gas found in the Earth's atmosphere.

Explain why evidence about the Earth's early atmosphere is limited.

Use Table 1, the evidence and your own knowledge to evaluate the theory that the Earth's early atmosphere was mainly carbon dioxide with little or no oxygen.