Final answer:
Nonmetals have properties such as being gas at room temperature, poor thermal conductors, and brittle. However, they are not good thermal conductors.
Step-by-step explanation:
One property of most NONMETALS is that they are gas at room temperature. This means that at normal room temperature and pressure, nonmetals exist as gases, such as oxygen and nitrogen.
Another property is that nonmetals are generally poor thermal conductors. They do not conduct heat well, which is why many nonmetals are used as insulators.
A third property of nonmetals is that they are usually brittle. Brittle materials break or shatter easily when subjected to stress, unlike metals that can undergo plastic deformation.
Therefore, the property that is NOT a property of most nonmetals is that they are good thermal conductors. Nonmetals do not conduct heat well like metals do.
Learn more about Properties of nonmetals