Carbon has all of these physical properties except _.
A. Dull solid B. Good conductor C. Solid state of matter D. Brittle
The correct answer and explanation is:
The correct answer is B. Good conductor.
Carbon is a unique element that exhibits a wide range of physical properties depending on its allotropes. The common allotropes of carbon include graphite, diamond, graphene, and amorphous carbon, and they each have distinct characteristics. Let’s break down the options:
- A. Dull solid: Carbon, particularly in its diamond form, is a clear and brilliant crystal. However, graphite, another allotrope of carbon, appears dull and is often described as a gray, powdery solid. Therefore, carbon can be a dull solid depending on its allotrope.
- B. Good conductor: This is the correct exception. While graphite is an excellent conductor of electricity due to its structure of free-moving electrons between layers, most forms of carbon (like diamond and amorphous carbon) are insulators. Diamond, for example, is a very poor conductor of electricity because its electrons are tightly bound in the crystal lattice and cannot move freely. Thus, carbon as a whole is not a good conductor of electricity in all its forms.
- C. Solid state of matter: At room temperature, carbon exists as a solid in all its allotropes. Whether it is in the form of diamond, graphite, or coal, carbon is typically found as a solid.
- D. Brittle: Many forms of carbon, such as graphite and coal, are brittle, meaning they break or crumble easily. Diamond, on the other hand, is extremely hard but can be brittle under certain conditions due to its crystal structure.
Thus, the main exception in the list is that carbon, in general, is not a good conductor of electricity, making option B the correct choice.