Chalk is an ionic compound. which is a property of all ionic compounds that makes chalk particularly useful for writing on a chalkboard?
a: a high melting point
b: hardness and brittleness
c: inability to dissolve in water
d: a multicolored appearance

B: hardness and brittleness

Explanation: Ionic compound is formed by the transfer of electrons. The ionic bond is formed between the metal and nonmetal where a metal loses electrons to form a positively charged cation and the non metal gains electrons to form negatively charged anion.

The two oppositely charged ions bound together by strong coloumbic forces and thus have high melting points, are hard and are able to dissolve in water.

The characteristic of chalk being an ionic compound is that it is hard and brittle and thus we can easily write on a chalkboard.

1/0.14nm = 10^10/1.4 a lot