Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Showing that air contains about one-fifth oxygen
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →A sample of dry air has a total volume of 200 cm³. Calculate:
(a)[1 mark]The volume of nitrogen in the sample.
(b)[1 mark]The volume of oxygen in the sample.
(c)[1 mark]The total volume of argon and carbon dioxide in the sample, using the approximate percentages in dry air.
Question 12
3 marks · Normal
Answer and see the solution →Below are two possible sources of error in an experiment using iron filings to measure the percentage of oxygen in air:
- The experiment is stopped after only one day, before the gas syringe reading stops changing.
- Only a small amount of iron filings is added, not in excess.
For each case, explain why the result might be inaccurate and whether it would make the calculated percentage of oxygen in air higher or lower than the correct value.
Question 13
4 marks · Normal
Answer and see the solution →The table shows results from an experiment to determine the composition of air.
Estimated composition of air. Gas Estimated percentage (%) Oxygen 20 Nitrogen 75 Argon 1 Carbon dioxide 0.04 (a)[2 marks]Compare the estimated percentage of nitrogen and oxygen to their approximate true values in dry air.
(b)[2 marks]Give two possible reasons why the estimated results might differ from the true values.
Question 14
1 mark · Normal
Answer and check →Which statement best describes how the percentage of oxygen in air can be found using an experiment with wet iron filings?
- A.Measure the increase in volume of gas.
- B.Measure the decrease in volume of gas in the apparatus.
- C.Record the temperature change of the conical flask.
- D.Count how quickly the iron changes colour.
Question 15
2 marks · Normal
Answer and see the solution →Name two gases that together make up almost all of dry, unpolluted air, and state their approximate combined percentage by volume.
Question 16
4 marks · Normal
Answer and see the solution →The diagram shows an apparatus used to investigate the percentage of oxygen in air using wet iron filings.
Apparatus for determining the percentage of oxygen using iron filings. (a)[2 marks]Describe the steps taken to set up and carry out this experiment.
(b)[1 mark]Suggest how the total volume of air present in the apparatus at the beginning can be measured.
(c)[1 mark]Explain why water is used when adding the iron filings.
Question 17
2 marks · Hard
Answer and see the solution →Name the two most abundant gases in dry, unpolluted air. State their approximate percentage composition by volume for each gas.
Question 18
5 marks · Hard
Answer and see the solution →The diagram below shows apparatus used to investigate the amount of oxygen in air using heated copper.
Apparatus for measuring oxygen in air with heated copper. Describe and explain how this experiment is carried out to determine the percentage of oxygen in air.
(a)[2 marks]State what change you would expect to see in the copper during the experiment, and explain your answer.
(b)[3 marks]Describe how you would use the readings from the gas syringes to calculate the percentage of oxygen in air. Include the calculation in your answer.
Question 19
2 marks · Hard
Answer and see the solution →Argon and carbon dioxide are both present in dry, unpolluted air. Which is present in a larger amount? Give an approximate percentage for both gases.