AQA GCSE Chemistry: Combined Science

Topic Questions

9.1 Formation of Earth's Atmosphere

1a4 marks

This question is about the composition of air. 

Draw one line from each substance in air to the approximate percentage of it there is in the current atmosphere.composition-of-air-match-up

1b1 mark

Which term best describes air? 

Tick () one box.

 Element  
 Compound  
 Mixture  

1c1 mark

Which group of the periodic table is oxygen located in?

1d2 marks

Oxygen levels have increased over the past 4.5 billions years. 

Explain why.

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2a2 marks

One theory is that the early atmosphere formed 4.6 billion years ago. 

The main gas present was carbon dioxide. 

Name two other gases that were present in the early atmosphere.

2b1 mark

What was the main source of the gases present in the early atmosphere? 

Tick (one box. 

 Volcanoes  
 Oceans  
 Trees  
 Sediment  
2c2 marks

Give the formula and state symbol of carbon dioxide.

Formula: _________________________

State symbol: ______________________

2d3 marks

Carbon dioxide levels have decreased over the past 4.6 billion years. 

Give three reasons why. 

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3a2 marks

This question is about the evolution of the atmosphere.

Figure 1 shows the changes that have occurred over the last 4.6 billion years. 

 Figure 1 
aqa-gcse-9-1e-tq3a-earths-atmosphere-pie-chart

Since the early atmosphere, water vapour levels have decreased.

Give two other differences between the composition of the early atmosphere and the atmosphere today. 

3b1 mark

What is the main gas in the atmosphere today? 

Tick (one box.

 oxygen  
 carbon dioxide  
 nitrogen  
 argon  
3c3 marks

Complete the sentences using the words in the box to describe what happened to the water vapour in the early atmosphere.

increased ocean volcanoes land
evaporated condensed decreased

The temperature of the earth's surface ____________________. 

The water vapour in the air ________________________ to form the _____________________________. 

3d1 mark

It is thought that algae evolved around 2.6 billion years ago.

They use carbon dioxide and water to produce oxygen.

Name the process they use to do this. 

Circle one answer. 

Combustion Respiration Photosynthesis
3e2 marks

Complete the word equation for this process.

__________________   +    water   →   _________________ +   oxygen

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4a3 marks

The composition of gases in the atmospheres of Mars and Earth are shown in Table 1 below. 

Table 1 
comparison-of-mars-and-earths-atmosphere

Complete the sentences using the information in the table to help you. 

The main gas on Mars is 

argon.

carbon dioxide.

nitrogen.

 

The gas in the table which is a compound is  

carbon dioxide.

nitrogen.

oxygen.

 

The gas in the table which is a noble gas is  

argon.

nitrogen.

oxygen.

4b
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1 mark

There was 95% carbon dioxide present in the Earth's early atmosphere.

Calculate the percentage decrease in carbon dioxide levels. 

4c2 marks

Explain why carbon dioxide levels have decreased since the early atmosphere. 

Tick () two boxes. 

 Locked up in fossil fuels   
 Taken in by volcanoes  
 Given off from burning fossil fuels  
 It dissolved in the oceans  
4d1 mark

Suggest why there is not much oxygen on Mars.

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1a1 mark

This question is about the atmosphere of Mars. 

The composition of its atmosphere is shown in the pie chart in Figure 1. 

Figure 1

aqa-gcse-9-1h-tq1a-atmosphere-pie-chart

Calculate the percentage of other gases on Mars. 

1b2 marks

Earth contains a high amount of oxygen compared to Mars.

Describe two other differences between the atmosphere of Earth and Mars. 

1c4 marks

It is thought when the Earth formed 4.5 billion years ago, the atmosphere was similar to that of Mars.

The growth of green plants and evolution of other organisms has changed the composition of the atmosphere over this period of time. 

Explain how. 

1d4 marks

Carbon dioxide is a greenhouse gas that contributes to global warming. 

Suggest four effects of global climate change. 

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2a2 marks

This question is about carbon dioxide.

Carbon dioxide gas levels have remained the same over the last 200 million years. 

Complete the dot and cross diagram to show the bonding carbon dioxide gas in Figure 1. 

Figure 1

0Wy8ONBm_blank-dot-and-cross-diagram-carbon-dioxide

2b3 marks

Explain why carbon dioxide is a gas at room temperature.

2c4 marks

Describe the natural processes which remove carbon dioxide from the atmosphere.

2d2 marks

Explain why carbon dioxide levels have risen again over the last 150 years.

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3a4 marks

Scientists have studied the atmosphere of different planets and think that Mars is simiilar to the earth's early atmosphere.

Table 1 compares the atmosphere of Mars and Earth. 

Table 1

Earth Mars 
nitrogen 78% nitrogen 3%
water trace water trace
carbon dioxide trace carbon dioxide 95%
oxygen 21% oxygen  trace
Average surface temperature -23 oC Average surface temperature 15 oC


Suggest why the composition of gases in the Earth's atmosphere has changed from millions of years ago. 

3b2 marks

The atmosphere of Titan, a moon of Saturn, consists of two main gases: nitrogen and methane. 

Table 2

Main gas in atmosphere Boiling point (oC) Percentage (%)
Methane -164 5
Nitrogen -196 95
Average surface temperature: -179 oC


Explain why methane falls as rain on this planet. 

3c2 marks

UV radiation from the Sun produces alkenes, such as propene and butene, from the methane in Titan's atmosphere.

Describe a test to show that butene is an unsaturated hydrocarbon.

Give the result of the test.

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4a1 mark

This question is about the evolution of the atmosphere. 

Name two gases that account for the majority of the Earth's atmosphere. 

4b2 marks

Explain why there is less water vapour in the atmosphere now, compared to three billion years ago. 

4c6 marks

It is thought that the Earth's early atmosphere was similar to the atmosphere found on Venus today. 

Table 1 shows the percentages of oxygen and carbon dioxide on each planet. 

Table 1

Gas Percentage (%) in Earth's atmosphere today Percentage (%) in Venus's atmosphere today
Oxygen 21 0
Carbon dioxide 0.04 97


Explain the processes that have led to the changes in oxygen and carbon dioxide levels on Earth. 

4d1 mark

Scientists cannot be certain about the proportion of gases that made up the early atmosphere of Earth.

Why not?

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1a6 marks

This question is about carbon dioxide in the atmosphere.

Up until 100 years ago and for the previous 200 million years, the amount of CO2 in the atmosphere had remained unchanged.

Describe the natural processes by which plants and marine life remove carbon dioxide from the atmosphere.

1b2 marks

The levels of carbon dioxide in the atmosphere have increased continually over the last one hundred years. 

Suggest two reasons for this increase.

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2a2 marks

This question is about the Earth and its atmosphere.

The theories about how Earth’s atmosphere has developed have evolved and changed over time. 

Suggest two reasons for this.

2b6 marks

The Earth and its atmosphere today are very unlike that of the early Earth as can be seen in Figure 1.

Figure 1

aqa-gcse-9-1m-sq-q2b-earths-developing-atmosphere

Describe and explain how the atmosphere of the early Earth has changed to the atmosphere that we know today.

2c3 marks

Around 60 million years ago a large meteorite struck the Earth. 

The impact heated limestone in the Earth’s crust, releasing huge quantities of carbon dioxide.

Explain how CO2 is released from limestone. 

You should include a balanced equation.

2d3 marks

The graph in Figure 2 shows the percentage of carbon dioxide in the Earth’s atmosphere over the last 50 years.

Figure 2

9-1-formation-of-earths-atmosphere-medium-q2d

Explain in as much detail as possible why we should be concerned about the information displayed in Figure 2.

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3a2 marks

Aside from water vapour, two main gases account for approximately 99% of the atmosphere.

Give the names of these gases.

3b4 marks

Scientists now believe that over three billion years ago, Earth’s atmosphere consisted of a mixture of water vapour, carbon dioxide, methane and ammonia. 

The mixture has changed significantly since then.

Suggest two reasons for the decrease in water vapour and two for the decrease in carbon dioxide.

3c2 marks

Describe how the gases in Earth’s early atmosphere (in the first billion years) formed.

3d3 marks

Describe the composition of the Earth's early atmosphere and name the planets it was most similar to.

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4a4 marks

This question is about the amount of nitrogen and oxygen in the atmosphere. 

Scientists study the atmosphere on planets and moons in the Solar System to get a better understanding of how the Earth’s atmosphere has changed.

It is suspected that the early Earth’s atmosphere resembled that of Mars today. 

The table shows data about the atmosphere of Mars and Earth today.

Earth today  Mars today
Nitrogen (N2) 78% Nitrogen (N2) 3%
Oxygen (O2) 21% Oxygen (O2) trace
Average surface temperature 15°C Average surface temperature −23°C


The percentages of N
2 and O2 in the Earth’s atmosphere of millions of years ago have changed.

Describe how the amounts of these gases have been changed and suggest what caused this change.

4b2 marks

What type of organism was first responsible for producing oxygen on Earth and when did this occur?

4c3 marks

Complete and balance the equation for photosynthesis, placing above the reaction arrow the condition needed for photosynthesis to occur.

__ CO2    +   ____   ⟶    __C6H12O6 + __O2

4d3 marks

Explain how deposits of limestone, coal and crude oil are formed.

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