Ionic bonding via electron transfer from X to Y

Steps:

• Element Y has more outer electrons, indicating higher electronegativity, so it gains electrons.
• XY conducts electricity when molten, characteristic of ionic compounds with free ions.
• Ionic bonding involves electron donation from less electronegative X to more electronegative Y.
• Thus, X donates to Y, forming ionic XY.

Why A is correct:

• Ionic bonding definition: complete electron transfer creates oppositely charged ions that conduct in molten state.

Why the others are wrong:

• B: Covalent bonding does not conduct electricity due to lack of ions.
• C: Electron sharing defines covalent bonding, not ionic.
• D: Electron sharing indicates covalent bonding; Y with more outer electrons would not donate.

Final answer: A