Question

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

Explanation:

Ionic compounds have strong electrostatic forces between ions. This gives them hardness. But when force is applied (like writing on a chalkboard), the layers of ions can shift, causing brittleness (breaking into small pieces that leave marks). High melting point (not relevant for writing), many ionic compounds dissolve in water (so "inability..." is wrong), and ionic compounds aren't necessarily multicolored.

Answer:

hardness and brittleness