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
751–760 of 991
Question 751
6 marks · Normal
Answer and see the solution →This question is about the structures of covalent molecules and giant covalent substances.
(a)[2 marks]Draw a dot-and-cross diagram (showing only outer shell electrons) for a molecule of water (H2O).
(b)[2 marks]Diamond and graphite are giant covalent structures made only of carbon atoms.
i. State how many other carbon atoms each carbon is bonded to in:
• diamond
• graphite
(c)[2 marks]Explain, in terms of structure and bonding, why diamond has a much higher melting point than water.
Question 752
6 marks · Normal
Answer and see the solution →This question tests your understanding of covalent bonding and how it affects the properties of substances.
(a)[2 marks]Calculate the total number of covalent bonds formed in a molecule of ethene (C2H4). Show your working.
(b)[4 marks]The table shows the electrical conductivity of three substances:
Substance Electrical conductivity Diamond Does not conduct Graphite Conducts C60 fullerene Does not conduct Explain, using their structure and bonding, why graphite conducts electricity but diamond and C60 fullerene do not.
Question 753
6 marks · Normal
Answer and see the solution →This question is about using dot-and-cross diagrams to interpret structures and properties.
(a)[2 marks]Draw a dot-and-cross diagram for a molecule of nitrogen, N2, showing only the outer shell electrons.
(b)[2 marks]Explain why nitrogen gas contains molecules, not a giant covalent structure like diamond and graphite.
(c)[2 marks]Explain why simple covalent molecules like N2 have much lower melting points than giant covalent structures such as diamond.
Question 754
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 755
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 756
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 757
1 mark · Easy
Answer and see the solution →State one reason why metals are good conductors of electricity.
Question 758
3 marks · Easy
Answer and see the solution →(a)[3 marks]Draw a simple 2D diagram to represent the metallic lattice of lithium metal. Label the positive metal ions and the sea of delocalised electrons.
Question 759
2 marks · Easy
Answer and see the solution →Explain why metals can be hammered into different shapes without breaking apart.
Question 760
3 marks · Easy
Answer and see the solution →Metals and their ion charges Metal Group Ion formed Sodium 1 Na+ Calcium 2 Ca2+ Aluminium 3 Al3+ Study the table above. For each metal, state how the charge on the ion relates to the number of delocalised electrons present in its metallic lattice.