Question

which of the following can easily form an ionic bond with a cation?
br
ne
nh4+
po43-

Explanation:

An ionic bond is formed between a cation (positively - charged ion) and an anion (negatively - charged ion).

• $\ce{Br}$ is a neutral atom.
• $\ce{Ne}$ is a noble gas atom and is neutral.
• $\ce{NH^{+}_{4}}$ is a cation.
• $\ce{PO^{3 - }_{4}}$ is an anion. Since an ionic bond is between a cation and an anion, $\ce{PO^{3 - }_{4}}$ (an anion) can form an ionic bond with a cation.

Answer:

$\ce{PO^{3 - }_{4}}$