Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Elements, Compounds and Mixtures
69 practice questions
Topics covered
Practice questions
11–20 of 69
Question 11
3 marks · Normal
Answer and see the solution →A sample contains 8 g of oxygen and 2 g of hydrogen. Describe whether this sample is a compound or a mixture, and state the formula of the compound (if any) that could be formed by these elements. Show your calculation.
Question 12
3 marks · Normal
Answer and see the solution →Paracetamol is a pure compound. Explain, using ideas about melting and boiling points, how you could prove that a sample of paracetamol is not a mixture. (3 marks)
Question 13
4 marks · Normal
Answer and see the solution →Sample table showing types of substances found in air. Substance Type Oxygen Water vapour Carbon dioxide Helium Dust particles (a)[3 marks]Complete the table by identifying each substance as an element, a compound, or a mixture. (3 marks)
(b)[1 mark]Is air itself an element, a compound, or a mixture? Explain your answer. (1 mark)
Question 14
1 mark · Normal
Answer and check →Which statement describes a key difference between a pure substance and a mixture?
- A.A pure substance has a sharp melting point; a mixture melts over a range.
- B.A pure substance can be separated by physical means only.
- C.A mixture contains only one type of atom.
- D.A pure substance always contains two different elements.
Question 15
2 marks · Normal
Answer and see the solution →State whether each of the following is an element, a compound, or a mixture: (a) Hydrogen chloride gas (b) Brass
Question 16
4 marks · Normal
Answer and see the solution →(a)[2 marks]Describe the melting point behaviour of a pure solid and a mixture during heating. (2 marks)
(b)[2 marks]A student finds that her sample of a white solid melts over the range 150°C to 163°C. What does this suggest about the purity of the sample? (2 marks)
Question 17
2 marks · Hard
Answer and see the solution →A student is given three samples: Sample A contains only carbon atoms, Sample B contains molecules of carbon dioxide, and Sample C contains both carbon dioxide and oxygen gas mixed together. Classify each sample as an element, a compound, or a mixture.
Question 18
5 marks · Hard
Answer and see the solution →A researcher is investigating two samples: Sample X is a pure substance, and Sample Y is a mixture. She records the melting and boiling behaviour of each sample while heating.
(a)[2 marks]Describe the expected melting behaviour of Sample X and Sample Y as they are heated.
(b)[2 marks]Explain how boiling point data can be used to decide whether Sample X or Sample Y is pure or a mixture.
(c)[1 mark]A sample melts sharply at 801°C and boils at exactly 1465°C with no temperature change during the phase transitions. State whether it is pure or a mixture, and justify your answer with evidence from the data.
Question 19
2 marks · Hard
Answer and see the solution →Give one way in which the proportions of substances in a mixture are different from those in a compound. Use an example to support your answer.
Question 20
1 mark · Easy
Answer and see the solution →Name the separation technique used to obtain coloured components from an ink sample.