Final answer:
When sodium, with an electronegativity value of 1.4, forms a bond with another element with a significantly different electronegativity, the bond is typically ionic. The classification is based on the difference in electronegativity values between the bonding atoms.
Step-by-step explanation:
If sodium has an electronegativity value of 1.4 and it were to bond with another element with a substantially different electronegativity value, the bond would likely be ionic. The type of bond formed between two elements depends on the difference in their electronegativity values. According to general guidelines, when the difference is very small or zero, the bond is covalent and nonpolar. Conversely, when the difference is large, the bond is either polar covalent or ionic. Given that common ionic compounds such as sodium chloride (NaCl) have a large electronegativity difference (Na 0.9, Cl 3.0, difference 2.1), and sodium has a low electronegativity, it tends to form ionic bonds with nonmetals which have a higher electronegativity. Therefore, the answer to the question is A. Ionic.
It is worth noting that the given value of 1.4 for sodium's electronegativity differs from the commonly accepted value of 0.9. However, this discrepancy doesn't affect the bond classification in this case.