Which is a binary ionic compound?

A binary ionic compound is composed of ions of two different elements. One of which is a metal, and the other a non-metal

I couldn't find options online for your question. But I can explain a little bit about it so you can identify the answer for yourself.

A binary ionic compound is made up of ions that have two different elements.

Of these two ions, one must be a metal and the other a nonmetallic.

The metallic atom will lose electrons, becoming a positive ion (cation), and the non-metallic atom will gain electrons, transforming into a negative ion (anion). Between them there is a very strong electrostatic attraction that is what holds them together.

Here are some examples of these types of compounds:

Sodium oxide: Na2O Calcium hydroxide: Ca (OH) 2 Aluminum hydride: AlH3 Hydrochloric acid: HCl