Question

the pair of elements that forms a bond with the most covalent character is na and cl. k and cl. o and cl. mg and cl.

Explanation:

To determine the bond with the most covalent character, we use the concept that covalent character increases as the electronegativity difference between atoms decreases. Metals (Na, K, Mg) and non - metal (Cl) form ionic bonds (large electronegativity difference), while non - metals (O and Cl) form a covalent bond (smaller electronegativity difference). Na, K, Mg are metals; O and Cl are non - metals. So the bond between O and Cl has the most covalent character.

Answer:

O and Cl.