Final answer:
The binary ionic compound among the options given is NaCl (aq), which is option D.
Step-by-step explanation:
The binary ionic compound among the options given is NaCl (aq), which is option D.
A binary ionic compound is formed when a metal cation and a non-metal anion combine through ionic bonding. In this case, sodium (Na) is a metal cation and chlorine (Cl) is a non-metal anion. They come together to form sodium chloride (NaCl).
Option B (BaSO4) is not a binary ionic compound as it contains multiple elements (barium, sulfur, and oxygen) bonded together.