Final answer:
Hydrogen is the most electronegative element among K, Na, and H, while sodium is the least electronegative according to Pauling's electronegativity values.
Step-by-step explanation:
In the context of electronegativity, which refers to an element's ability to attract electrons towards itself, we analyze three particular elements: potassium (K), sodium (Na), and hydrogen (H). According to Pauling's electronegativity values, electronegativity generally increases as you move diagonally from the lower left to the upper right of the periodic table.
The most electronegative of the given elements is hydrogen, with an electronegativity of 2.20. On the other hand, potassium (K) and sodium (Na) are both less electronegative, but of the two, sodium is less electronegative than potassium. This makes sodium the least electronegative of the three elements listed.