Answer: Option D K and CI.
Step-by-step explanation:
The pair of elements that would NOT form a covalent bond is option d, K and Cl.
Covalent bonds occur between nonmetal atoms, as they share electrons to achieve a stable electron configuration. In option d, K represents the element potassium, which is a metal, while Cl represents chlorine, a nonmetal. Metals and nonmetals generally form ionic bonds rather than covalent bonds.
Ionic bonds occur when one atom transfers electrons to another atom. In this case, potassium would transfer one electron to chlorine to achieve stability. This results in the formation of K+ and Cl- ions, which are attracted to each other due to their opposite charges.
Therefore, the pair of elements K and Cl would not form a covalent bond, but rather an ionic bond.