Which of the following substances has a network of covalently bonded atoms?

A. H2O

B. CO2

C. Diamond

D. Methane (CH4)

Which substance is expected to have the lowest melting point due to weak intermolecular forces?

A. Silicon dioxide (SiO2)

B. Diamond

C. CO2

D. Graphite

Which of the following is NOT a property of substances with a network of covalently bonded atoms?

A. High electrical conductivity

B. High melting point

C. High boiling point

D. Hardness

Which of the following substances is a molecular solid with weak intermolecular forces?

A. Graphite

B. Silicon dioxide (SiO2)

C. H2O

D. Diamond

Which substance has layers of covalently bonded atoms that can slide over each other?

A. Diamond

B. CO2

C. Graphite

D. H2O

a) Describe the properties of molecules that exhibit weak intermolecular forces. [2]

b) Explain why substances with weak intermolecular forces, such as H2O and CO2, have low melting and boiling points. [3]

a) What is meant by a "network of covalently bonded atoms"? [2]

b) Using diamond as an example, explain how its covalent structure contributes to its high melting and boiling points. [3]

a) Silicon dioxide (SiO2) is another example of a substance with a network covalent structure. Describe the arrangement of atoms in silicon dioxide. [2]

b) How does the structure of silicon dioxide compare to that of graphite in terms of their melting and boiling points? [3]

a) Why are substances like diamond and graphite, which are both forms of carbon, considered to have network covalent structures? [2]

b) Compare the electrical conductivity of diamond and graphite. Provide a reason for the observed difference. [3]

c) Which of the two, diamond or graphite, is harder and why? [2]

a) Explain the term "intermolecular forces". [2]

b) How do intermolecular forces affect the physical properties of a substance, such as its boiling point? [3]

c) Why does H2O have a higher boiling point than CO2, even though both have weak intermolecular forces? [3]

Which of the following best describes the forces between CO2 molecules?

A. Ionic bonds

B. Covalent bonds

C. Metallic bonds

D. Van der Waals forces

Which of the following substances is expected to be the hardest due to its covalent network structure?

A. H2O

B. CO2

C. Diamond

D. Methane (CH4)

Which of the following substances is NOT a covalent network solid?

A. Silicon dioxide (SiO2)

B. Diamond

C. Graphite

D. CO2

Which of the following substances has the highest boiling point due to its covalent network structure?

A. H2O

B. CO2

C. Diamond

D. Methane (CH4)

Which substance is expected to be a good conductor of electricity due to its covalent structure?

A. Diamond

B. CO2

C. Graphite

D. H2O

a) What is the significance of the tetrahedral arrangement in covalent structures like diamond and silicon dioxide? [3]

b) How does the structure of silicon dioxide differ from that of water in terms of bonding? [2]

c) Given that both water and silicon dioxide have oxygen atoms, why is water a liquid at room temperature while silicon dioxide is a solid? [3]

a) Describe the structure of graphite and explain why it is used as a lubricant. [3]

b) How does the layered structure of graphite contribute to its ability to conduct electricity? [2]

c) Why is graphite, despite being made of carbon atoms like diamond, opaque and not shiny? [3]

a) Define the term "network covalent structure". [2]

b) Explain why substances with a network covalent structure, such as diamond and silicon dioxide, are typically hard and have high melting points. [3]

c) Given that both diamond and graphite are forms of carbon, why is only graphite able to conduct electricity? [3]

d) How does the structure of silicon dioxide differ from carbon dioxide, even though both contain silicon or carbon bonded to oxygen? [3]

a) Describe the role of intermolecular forces in determining the state of a substance at room temperature. [3]

b) Why does water, despite having weak intermolecular forces, exist as a liquid at room temperature while many other substances with similar forces exist as gases? [3]

c) Explain the difference in the physical properties of diamond and graphite, given that both are forms of carbon. [4]

d) How does the structure of silicon dioxide make it suitable for use in the electronics industry? [3]

a) Why are substances like diamond and silicon dioxide poor conductors of electricity, despite being made up of covalently bonded atoms? [3]

b) Explain the significance of the tetrahedral arrangement in substances with a network covalent structure. [3]

c) How does the presence of weak intermolecular forces in a substance like CO2 influence its physical state at room temperature? [3]

d) Given the examples of H2O, CO2, diamond, and graphite, explain the relationship between structure and properties in covalent substances. [4]