Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Covalent Bonding
68 practice questions
Topics covered
Practice questions
51–60 of 68
Question 51
4 marks · Normal
Answer and see the solution →The table shows the melting points and hardness for three forms of carbon.
Properties of carbon allotropes Allotrope Melting point/°C Hardness Diamond 3550 Very hard Graphite 3600 Soft C60 fullerene 280 Soft (a)[2 marks]Using only the data, identify which allotrope(s) have a giant covalent structure. Explain your reasoning.
(b)[2 marks]Using the data and your knowledge, explain why C60 fullerene has a lower melting point than graphite.
Question 52
1 mark · Normal
Answer and check →Which statement correctly compares the electrical conductivity of diamond, graphite, and C60 fullerene?
- A.Only graphite conducts electricity because it has delocalised electrons.
- B.Only diamond conducts electricity because it has a giant covalent structure.
- C.Diamond and C60 fullerene both conduct electricity, but graphite does not.
- D.All three conduct electricity equally well.
Question 53
2 marks · Normal
Answer and see the solution →Describe the bonding in diamond in terms of the arrangement of carbon atoms and the bonds formed.
Question 54
4 marks · Normal
Answer and see the solution →Diamond is a non-conductor of electricity and is very hard, while graphite is soft but conducts electricity.
(a)[2 marks]Explain, in terms of bonding and structure, why diamond does not conduct electricity.
(b)[2 marks]Explain, using bonding and the arrangement of atoms, why graphite is soft.
Question 55
2 marks · Hard
Answer and see the solution →Diamond is used for industrial cutting tools, while graphite is used as a lubricant. Explain, in terms of structure and bonding, why graphite can be used as a lubricant but diamond cannot.
Question 56
5 marks · Hard
Answer and see the solution →The three allotropes of carbon—diamond, graphite, and C60 fullerene—have different abilities to conduct electricity.
(a)[1 mark]State which, if any, of these allotropes can conduct electricity.
(b)[4 marks]For each allotrope, explain your answer by referring to their bonding and the movement of electrons.
Question 57
2 marks · Hard
Answer and see the solution →Describe the structure and bonding in C60 fullerene, referring to how carbon atoms are arranged and bonded in this allotrope.
Question 58
5 marks · Easy
Answer and see the solution →(a)[1 mark]Define a covalent bond.
(b)[2 marks]Explain, in terms of electrostatic attraction, how a covalent bond holds two atoms together.
(c)[1 mark]State one reason why many substances with simple molecular structures have low melting points.
(d)[1 mark]Methane, CH, is a gas at room temperature. Explain why, using your knowledge of bonding and structure.
Question 59
5 marks · Easy
Answer and see the solution →(a)[2 marks]Draw a dot-and-cross diagram to show the bonding in a molecule of hydrogen chloride (HCl).
(b)[1 mark]State how many covalent bonds are present in a molecule of hydrogen chloride.
(c)[2 marks]Chlorine is a gas at room temperature, but water (HO) is a liquid. Using ideas about relative molecular mass, explain this difference.
Question 60
5 marks · Easy
Answer and see the solution →(a)[2 marks]Hydrogen (H) and carbon dioxide (CO) are both covalent molecules. Calculate the relative molecular mass (M) of each molecule. (Relative atomic masses: H = 1, C = 12, O = 16)
(b)[2 marks]Which of these molecules would you expect to have a higher boiling point? Explain your answer in terms of molecular mass and intermolecular forces.
(c)[1 mark]State the type of bonding present in both hydrogen and carbon dioxide molecules.