Answer: KOH
Explanation:
Being KOH the only not binary compound it is the candidate to be the one with two different type of bondings.
In fact, KOH is a ionic compound because the cation K⁺ forms a ionic bond with the anion OH⁻.
On the other hand, the oxigen and hydrogen atoms in OH⁻ are covalently bonded.
The ionic bond is the result of the union of two atoms with a high elecronegativity difference, while the covalent bonding is the result of a combination of two atoms whose electronegativities is not so different.
Being K and alkali metal (the elements with lowest electronegativity) and OH⁻ an anion, they easily form the ionic bond.
From tables, the electronegativity of H is 2.20 and the electronegativity of O is 3.16, which leads to a difference of 3.16 - 2.20 = 0.96. This difference is not enough to form ions but covalent bonds. That is why the bond O-H is covalent.
When you analyze the bonds of the other choices, N-O, C-H, and H-Br, y ou conclude that the electronegativities lead to covalent bonds too.
