Final answer:
Out of the atom pairs O and H, B and H, P and F, C and Cl, and Ca and Cl, only the bond between Ca and Cl is considered ionic due to a large electronegativity difference. Other bonds are covalent with different levels of polarity.
Step-by-step explanation:
To determine whether the bonds formed between the following pairs of atoms are ionic, we need to look at the electronegativity difference between the atoms. A bond is generally considered ionic if the electronegativity difference is greater than approximately 1.7. Let's explore each pair:
O and H: Oxygen (O) has a high electronegativity, and hydrogen (H) has a lower one, but the difference is not large enough to make the bond ionic. It is a definitely polar covalent bond.
B and H: Boron (B) and hydrogen (H) have a small electronegativity difference, forming a slightly polar covalent bond.
P and F: Phosphorus (P) and fluorine (F) have a significant electronegativity difference. The bond formed between them could be considered likely ionic, but it is typically still polar covalent.
C and Cl: Carbon (C) and chlorine (Cl) have a noticeable electronegativity difference, but usually, this bond is considered definitely polar covalent.
Ca and Cl: Calcium (Ca) and chlorine (Cl) have a very high electronegativity difference, which results in a likely ionic bond.
Out of the pairs presented, the bond between Ca and Cl is ionic. The other bonds listed are covalent, with varying degrees of polarity.