Final answer:
Semiconductance is the property of materials used in computer chips that allows them to function as switches, turning electricity on and off. Silicon is a commonly used semiconductor in computer chips.
Step-by-step explanation:
The property of the materials used in computer chips that makes them useful as switches that turn electricity on and off is semiconductance. Semiconductors are materials with intermediate conductivity between conductors and insulators. They can be made conductive or insulating under specific conditions. Silicon is the most commonly used semiconductor in computer chips.