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
121–130 of 161 · Hard
Question 121
8 marks · Hard
Answer and see the solution →This question is about the differences in properties between substances with simple molecular structures and those with giant covalent structures.
(a)[2 marks]Explain why substances with simple molecular structures, such as chlorine (Cl₂), have low melting and boiling points.
(b)[3 marks]Diamond and graphite are both forms of carbon, but diamond is much harder than graphite. Explain, in terms of structure and bonding, why diamond is harder than graphite.
(c)[3 marks]State and explain whether Cl₂ can conduct electricity. Then compare this with the ability of diamond to conduct electricity, explaining your reasoning.
Question 122
7 marks · Hard
Answer and see the solution →This question is about how the physical properties of substances are linked to their structures and electrical conductivity.
(a)[0 marks]The table shows data for some simple molecular and giant covalent substances:
Melting and boiling points of selected substances. Substance Relative molecular mass / Mr Melting point / °C Boiling point / °C Chlorine (Cl₂) 71 -101 -34 Bromine (Br₂) 160 -7 59 Iodine (I₂) 254 114 184 Diamond – 3550 4830 (b)[2 marks]Using data from the table, describe and explain how the melting and boiling points of the halogens change as the relative molecular mass increases.
(c)[2 marks]Explain why the melting point of diamond is much higher than those of the halogens listed, using ideas about structure and bonding.
(d)[3 marks]State whether graphite conducts electricity. Suggest, based on your knowledge of its structure, why this is different from diamond and the halogens.
Question 123
7 marks · Hard
Answer and see the solution →This question is about how the type of structure affects properties in covalent and giant covalent substances.
(a)[2 marks]Explain what is meant by a 'simple molecular structure', using water (H₂O) as an example.
(b)[3 marks]Compare the structure and bonding found in C₆₀ fullerene with that in graphite.
(c)[2 marks]State which would have a higher melting point, graphite or C₆₀ fullerene. Explain your answer in terms of their bonding and structures.
Question 124
2 marks · Hard
Answer and see the solution →Explain, in terms of electrostatic forces, how metallic bonding holds a pure metal such as aluminium together. Your answer should refer specifically to the particles involved.
Question 125
5 marks · Hard
Answer and see the solution →Zinc is used to galvanise iron to prevent rusting because it is strong and resistant. Answer the following about the properties of zinc metal and its bonding.
(a)[2 marks]State and explain, in terms of metallic bonding, why zinc conducts electricity.
(b)[2 marks]Zinc can be hammered into thin sheets. Explain why this is possible, referring to its structure and bonding.
(c)[1 mark]Zinc has a high melting point. Explain this property in terms of attraction between its particles.
Question 126
2 marks · Hard
Answer and see the solution →Draw a simple 2D diagram to represent the arrangement of particles in a piece of barium metal. Clearly label the positive ions and the sea of delocalised electrons.
Question 127
2 marks · Hard
Answer and see the solution →Explain why pure, solid silver chloride does not conduct electricity, but when dissolved in water, it does.
Question 128
5 marks · Hard
Answer and see the solution →A teacher tests the electrical conductivity of four substances in different states. The results are shown in the table below.
Conductivity of substances in different states Substance State Conducts electricity? Potassium nitrate Solid No Potassium nitrate Aqueous Yes Sulfur dioxide Liquid No Lead(II) bromide Molten Yes (a)[1 mark]Identify which of the substances in the table are ionic compounds.
(b)[2 marks]Explain why potassium nitrate conducts electricity when dissolved in water but not as a solid.
(c)[2 marks]Suggest why sulfur dioxide does not conduct electricity, even when liquid. Use your knowledge of bonding.
Question 129
2 marks · Hard
Answer and see the solution →Explain, with reference to structure and particles, why molten lead(II) bromide can conduct electricity.
Question 130
2 marks · Hard
Answer and see the solution →State the name given to (a) the positive electrode and (b) the liquid or solution that contains ions and undergoes electrolysis. Give both answers.