Metalloids are elements that exhibit properties that are characteristic of both metals and nonmetals. They are located on the periodic table along the zigzag line between metals and nonmetals. The metalloids include elements such as boron, silicon, germanium, arsenic, antimony, tellurium, and astatine.

Properties of Metalloids:
1. Electrical Conductivity:
- Metalloids can conduct electricity, but not as effectively as metals.
- They have intermediate conductivity, which means they can conduct electricity under certain conditions.
- Silicon, for example, is a semiconductor and is widely used in electronic devices.

2. Thermal Conductivity:
- Metalloids have varying degrees of thermal conductivity.
- They can conduct heat to some extent, but not as well as metals.
- This property is important in applications such as thermoelectric devices.

3. Brittle Solids:
- Metalloids are generally brittle solids, meaning they are prone to fracture when subjected to stress or pressure.
- For example, boron is a hard, brittle solid that is used in the production of bulletproof vests.

4. Variable Chemical Properties:
- Metalloids can exhibit a range of chemical properties, depending on the specific element.
- For instance, boron can act as an acid or a base depending on the reaction conditions.
- Silicon is a key component of many minerals and is widely used in the production of glass and ceramics.

5. Nonmetallic Oxides:
- Metalloids tend to form oxides that are more acidic than those of metals.
- For example, silicon dioxide (silica) is a common compound found in sand and is used in the production of glass.

6. Allotropy:
- Some metalloids exhibit allotropy, which is the ability to exist in multiple forms or crystal structures.
- For instance, carbon is a metalloid that can exist as both diamond and graphite, each with different properties.

In summary, metalloids possess properties that are intermediate between those of metals and nonmetals. They exhibit electrical conductivity, thermal conductivity to varying degrees, brittleness, and variable chemical properties. Metalloids also tend to form nonmetallic oxides and can exhibit allotropy. Therefore, the correct answer is option 'C' - metalloids have properties that are characteristic of both metals and nonmetals.

Metalloids are all solid at room temperature. They can form alloys with other metals. ... The physical properties of metalloids tend to be metallic, but their chemical properties tend to be non-metallic. The oxidation number of an element in this group can range from +5 to -2, depending on the group in which it is located.