Answer:
KCl
Explanation:
Look at the electronegativity differences between the pairs of elements:
KCl: 3.16 - 0.82 = 2.34
BeCl: 3.16 - 1.57 = 1.59
LiCl: 3.16 - 0.98 = 2.18
ClO: 3.44 - 3.16 = 0.28
KCl has the highest electronegativity difference; thus it is the most ionic bond of the 4.
