Answer:
A. NH₄⁺
Step-by-step explanation:
Acids and bases are specific substances that have unique reactions with each other.
Brønsted-Lowry Acids and Bases
Brønsted-Lowry acids are defined as substances that can donate a proton. Brønsted-Lowry bases are substances that can accept a proton. So, by this definition, an acid-base reaction is a reaction where protons are transferred. It is important to note that in most cases protons will be represented as H⁺.
Identifying Acids
Brønsted-Lowry acids will have an extra H⁺ that can be removed. So, we can automatically eliminate C and D as answers because neither of them contains hydrogen. Then, looking at the Lewis structures for A and B we can tell that the bond between the nitrogen and hydrogen is weaker in NH₄⁺ than in NH₃. This means that NH₄⁺ is more likely to donate a proton. Thus, NH₄⁺ is a Brønsted-Lowry acid.