Answer: Option (3) is the correct answer.
Explanation:
Molecular substances are the substances which have two or more different atoms attached together.
Molecular substances have weak intermolecular forces of attraction thus, they have low melting and boiling point.
They have poor electrical conductivity as the bond formation in molecular compounds is covalent. Therefore, they also have poor heat conductivity.
Hence, out of the given options low melting point is the characteristic property of molecular substances.
Answer is: 3) low melting point.
Molecular substances are usually gases and liquids with low melting point.
The melting point depends on the strength of the intermolecular forces.
Intermolecular forces are the forces between molecules.
Molecular substances have bad heat conductivity and electrical conductivity.
Molecular substances are bonded with covalent bonds.