Diamond is a A. good conductor and soft B. non-conductor and soft C. non-conductor and hard D. good conductor and hard

The correct answer is: C. non-conductor and hard

Diamond is a non-conductor of electricity and heat. It is the hardest natural substance on Earth. It is made up of carbon atoms that are arranged in a tetrahedral structure. This structure makes diamond very strong and resistant to wear and tear. Diamond is also a very good insulator, which means that it does not conduct electricity or heat well.

Option A is incorrect because diamond is a non-conductor of electricity.

Option B is incorrect because diamond is hard, not soft.

Option D is incorrect because diamond is a non-conductor of electricity, not a good conductor.