Which phrase best describes a 0.012m solution of an acid that ionizes only slightly in water?

Answer: a 0.012 M solution of an acid that ionizes only slightly in water is dilute and weak.

Explanation:

0.012 M counts for the molarity of the acid.

Molarity is a measure con concentration.

Molarity is the number of moles of solute dissolved in 1 liter of solution.

So a molarity of 0.012 M means that there are 0.012 moles of the acid present in one liter of solution. That is a low concentration, meaning that the acid is diluted.

The fact that the acid ionizes slightly means that the acid is weak, that is only a small part of the moleculas of the acid will transform into H₃O⁺ ions (hydronium ions). This kind of acids is refered as weak acids (for example acetic acid), while acids that ionizes completely are the strongest acids (for example H₂SO₄)