The correct Lewis structures are:
a. O (oxygen),
c. Kr (krypton),
f. Ga (gallium),
g. S (sulfur).
Lewis structures are representations of the valence electron arrangement in atoms and molecules. Each letter corresponds to a specific atom:
a. O (oxygen): Oxygen has six valence electrons. The Lewis structure (single bonds and lone pairs) for oxygen is typically represented as two dots around the symbol, forming a doublet.
c. Kr (krypton): Krypton is a noble gas and has a full valence shell, so its Lewis structure is depicted with eight electrons around the symbol, signifying a stable octet.
f. Ga (gallium): Gallium has three valence electrons. The Lewis structure for gallium would typically involve three dots around the symbol.
g. S (sulfur): Sulfur has six valence electrons. The Lewis structure for sulfur commonly includes six dots around the symbol, forming a stable doublet and an incomplete octet.
These representations help visualize the electron distribution in atoms, indicating bonding and lone pairs. Keep in mind that the actual Lewis structure may vary based on specific bonding patterns and molecular contexts.