Macromolecule (Giant Molecular Structure)

Diamond and graphite are macromolecules.

Which statement about diamond and graphite is not correct?

• They are giant structures with high melting point

• They are non-conductors of electricity

• They only contains atoms of a non-metal

• They have covalent bonds between the atoms

Two statements about diamond are given.

1 Diamond has a giant three-dimensional covalent structure of carbon atoms

2 Diamond is one the hardest substance known

Which is correct?

• Both statements are correct and statement 1 explains statement 2

• Statement 1 is correct but statement 2 is incorrect

• Statement 2 is correct but statement 1 is incorrect

The 'lead' in a pencil is made of a mixture of graphite and clay.

When the percentage of graphite is increased, the pencil slides across the paper more easily.

Which statement explains this observation?

• Graphite has a high melting point

• Graphite is a form of carbon

• Graphite is a lubricant

• Graphite is a non-metal

Which of the following does not have a giant structure?

• Diamond

• Graphite

• Iodine

• Silicon dioxide

Which statement about different forms of carbon is correct?

• Graphite and diamond conduct electricity

• Graphite conducts electricity but diamond does not

• Diamond conduct electricity but graphite does not

Which statement best explains why diamond has a high melting point?

• 
  It has strong covalent bonds

• A large amount of energy is needed to break its strong covalent bonds

• A large amount of energy is needed to break its bonds

Which of the following has a giant covalent structure?

• carbon dioxide

• magnesium oxide

• silicon dioxide

Why does silicon dioxide have such a high melting point?

• 
  Because the silicon and oxygen atoms are held by strong intermolecular forces

• 
  Because the silicon and oxygen atoms are held by many strong covalent bonds

• 
  Because there are strong electrostatic forces between the silicon and oxygen atoms

Why is graphite useful for pencil leads?

• It is hard with a high melting point

• It is black and slippery

• It is shiny and melts easily

What type of structure do both diamond and graphite have?

• A giant covalent structure

• A giant ionic lattice structure

• 
  A simple molecular structure