Hydrocarbons | Starter Quiz | Oak National Academy

Which of the following is a characteristic of molecular compounds?

• Composed of metal atoms

• Made from metal and non-metal atoms

• Formed from non-metal atoms

Answer explanation

Molecules are covalent substances. Covalent bonds normally only form between non-metal atoms.

In distillation, what characteristic is primarily used to separate substances in a mixture?

• Density

• Boiling point

• Molecular weight

• Colour

Answer explanation

Substances are separated based on their boiling points in distillation. The substance with the lowest boiling point will evaporate/boil first, and then pass through a condenser (where it condenses) and then collect in another container.

Carbon will form a maximum of ___ bonds to other atoms.

Answer explanation

Most of the time carbon will form 4 bonds to other atoms (e.g. CH₄, or CO₂ - two double bonds). However, it can form 3 bonds to other atoms in structures like graphite and graphene (as one electron per atom becomes delocalised).

When oxygen atoms bond together to make diatomic oxygen molecules (O₂), this is known as a double covalent bond.

• True

• False

Answer explanation

True. Covalent bonds form as pairs of a electrons. Multiple pairs of electrons can be shared between two atoms.

Which property increases as the strength of intermolecular forces increases?

• Electrical conductivity

• Malleability

• Boiling point

• Solubility in water

Answer explanation

Intermolecular forces of attraction hold molecules together. The stronger they are, the more energy needed to overcome them. This increases the temperature a substance boils at (turns from liquid to gas).

Select all the true statements about simple molecular substances.

• Low melting points

• Cannot conduct electricity

• High melting points

• Conduct electricity only when molten or dissolved

• Conduct electricity all the time

Answer explanation

Simple molecular substances cannot conduct electricity as they have no free moving charge carriers. They have low melting points as they have weak intermolecular forces of attraction between molecules that require little energy to overcome.