Grade 12 Chemistry Quiz

What does the word giant mean in the context of giant covalent structures?

• Very large in size

• Made up of many atoms

• Highly reactive

• Extremely dense

Explain why diamond is very hard, whereas graphite is so soft that it can be used in pencils or as a lubricant.

• Diamond has a layered structure, while graphite has a three-dimensional structure.

• Diamond has stronger covalent bonds than graphite.

• Diamond has a higher melting point than graphite.

• Diamond has a higher density than graphite.

Explain why graphite is less dense than diamond.

• Graphite has a layered structure, while diamond has a three-dimensional structure.

• Graphite has weaker covalent bonds than diamond.

• Graphite has a lower melting point than diamond.

• Graphite has a higher density than diamond.

Although graphite is very much softer than diamond, both substances have very high melting points. Explain why that is.

• Graphite has stronger covalent bonds than diamond.

• Graphite has a layered structure, while diamond has a three-dimensional structure.

• Graphite has a higher density than diamond.

• Graphite has a higher boiling point than diamond.

Explain why graphite conducts electricity whereas diamond doesn't.

• Graphite has a layered structure, allowing delocalized electrons to move freely.

• Graphite has stronger covalent bonds than diamond.

• Graphite has a higher density than diamond.

• Graphite has a higher melting point than diamond.

What is the structure of silicon dioxide?

• Layered structure

• Three-dimensional structure

• Linear structure

• Spherical structure

Why does silicon dioxide have a high melting point?

• Silicon dioxide has strong covalent bonds.

• Silicon dioxide has a layered structure.

• Silicon dioxide has weak attractions with solvent molecules.

• Silicon dioxide has a low density.

Why doesn't silicon dioxide conduct electricity?

• Silicon dioxide has a layered structure, preventing the movement of electrons.

• Silicon dioxide has weak covalent bonds.

• Silicon dioxide has a high density.

• Silicon dioxide has no free electrons to move.

Giant lattice structure held together by attraction between positive and negatively charged ions.

• simple covalent molecules

• metallic

• ionic

• giant covalent

What structure is shown in the diagram?

• diamond

• graphite

• carbon nanotube

• graphene