Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Principles of Chemistry
991 practice questions
Topics covered
- States of Matter102 practice questions
- Elements, Compounds and Mixtures69 practice questions
- Atomic Structure108 practice questions
- The Periodic Table103 practice questions
- Chemical Formulae, Equations and Calculations Part 119 practice questions
- Chemical Formulae, Equations and Calculations Part 2144 practice questions
- Ionic Bonding143 practice questions
- Covalent Bonding68 practice questions
- Metallic Bonding19 practice questions
- Electrolysis198 practice questions
Practice questions
41–50 of 423 · Normal
Question 41
6 marks · Normal
Answer and see the solution →A student investigates how quickly a purple solid, potassium manganate(VII), spreads through water and compares this to how a coloured gas spreads through air.
(a)[2 marks]Describe, using the particle model, what happens to potassium manganate(VII) when it is placed in water.
(b)[1 mark]State what is meant by the term 'solute' in this experiment.
(c)[2 marks]Explain why the potassium manganate(VII) spreads more slowly in water than a coloured gas spreads in air.
(d)[1 mark]State what is meant by a 'saturated solution.'
Question 42
6 marks · Normal
Answer and see the solution →Two students investigate the diffusion and solubility of a substance.
(a)[2 marks]Student 1 observes that when a cotton wool ball soaked in concentrated ammonia solution is placed at one end of a closed tube, and a cotton wool ball soaked in concentrated hydrochloric acid is placed at the other end, a white ring of ammonium chloride forms closer to the hydrochloric acid end.
Explain why the white ring does not form in the centre of the tube.
(b)[2 marks]Student 2 measures how much of a solid, potassium nitrate, can dissolve in 100 g of water at different temperatures.
Describe how the student can use the results to draw a solubility curve.
(c)[1 mark]State how a solubility curve can be used to determine the mass of potassium nitrate that will dissolve at a specific temperature.
(d)[1 mark]Give one reason why diffusion of gases occurs faster than diffusion of solids dissolved in water.
Question 43
6 marks · Normal
Answer and see the solution →A student performs experiments to investigate how much of a solute dissolves in water, and how diffusion works in gases.
(a)[2 marks]The solubility of potassium nitrate in water at 40°C is 64 g per 100 g of water.
Calculate the maximum mass of potassium nitrate that will dissolve in 250 g of water at this temperature.
(b)[3 marks]In a diffusion tube experiment, the white ring of ammonium chloride forms 12 cm from the ammonia end and 8 cm from the hydrochloric acid end.
Calculate the ratio of speed of ammonia particles to hydrogen chloride particles.
(c)[1 mark]State one reason why it is important to measure the water mass carefully in a solubility experiment.
Question 44
6 marks · Normal
Answer and see the solution →A teacher asks the class to consider a scenario: 'Chlorine gas and a solid sugar cube are each placed in the opposite ends of two sealed glass tubes filled with air. Both tubes are left for several hours at room temperature.'
(a)[2 marks]Explain what happens to the chlorine gas in terms of diffusion.
(b)[2 marks]Describe what would happen to the sugar cube over time and give a reason using particle ideas.
(c)[2 marks]State what is meant by a solution, referring to both the sugar experiment and the key terms 'solute' and 'solvent.'
Question 45
2 marks · Normal
Answer and see the solution →State whether each of the following substances is an element, a compound, or a mixture. (a) Silver (b) Seawater
Question 46
4 marks · Normal
Answer and see the solution →(a)[2 marks]Explain how you could use melting point to distinguish between pure salt and a mixture of salt and sand. (2 marks)
(b)[2 marks]Predict how the boiling point of a mixture of water and alcohol compares to the pure substances, and explain your answer. (2 marks)
Question 47
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 48
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 49
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 50
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.