Which of the following represents the possible structure of a binary acid? Remember, a binary acid is an acid that does not contain oxygen. If we take a look at the first one, we have a covalent compound beginning with the hydrogen. So yes, it is an acid, but the presence of oxygen means it is not a binary acid.
The next one isn't an acid at all. It's barium chloride. There's no H ions anywhere. The next one we have is HF. It's covalent. It starts with a hydrogen, so it's an acid. It has no oxygen, so it is a binary acid. This is hydrofluoric acid.
Then finally we have LIH. Now here, this is an ionic compound and more importantly, it is a metal cation connected to a basic anion. It is Li positive, H minus. This is an example of a base. Now if you didn't see that, make sure you go back and take a look at my videos where I talk about bases and the introduction of them. So here this would be a base.
Out of all the choices, the only one that is a binary acid is option C.