Final answer:
Carbon is the nonmetal among the listed options, as it forms covalent bonds and is placed on the right side of the periodic table, common for nonmetals.
Step-by-step explanation:
The main answer to the question, "Which of the following is a nonmetal?", is carbon. Looking at the provided information, we can see that carbon is classified as a nonmetal because it is found in group 14 of the periodic table, which contains nonmetals. Other substances such as potassium, calcium, lead, and uranium are metals, with uranium being an inner transition metal specifically. An explanation for why carbon is a nonmetal is due to its ability to form covalent bonds and its placement on the right side of the periodic table, where nonmetals are generally located.