Which of the following is a characteristic property of ionic compounds?
a. they have low melting points.
b. they have low boiling points.
c. they form hard, brittle crystals with characteristic shapes.
d. they contain no charged particles.

Option (c) is the correct answer.

Explanation:

Ionic compounds are the compounds in which there occurs transfer of one or more number of electrons from one atom to another.

Also, due to difference in electronegativity of the combining atoms there will be formation of partial positive and partial negative charges.

So, ionic compounds are held more tightly due to force of attraction between the opposite charges. Hence, they have high melting and boiling points.

Whereas generally, ionic solids are hard but due to the presence of repulsive forces between the similar ions disrupts the crystal lattice. Hence, ionic compounds have brittle crystals.

Thus, we can conclude that they form hard, brittle crystals with characteristic shapes is a characteristic property of ionic compounds.