\begin{tabular}{|l|l|l|l|}
\hline \multicolumn{1}{|c|}{ Chemical Name } & \multicolumn{1}{|c|}{ Chemical Formula } & \multicolumn{1}{c|}{ Chemical Name } & \multicolumn{1}{c|}{ Chemical Formula } \\
\hline acetate & [tex]$C _2 H _3 O _2^{-}$[/tex] & nitrite & [tex]$NO _2^{-}$[/tex] \\
\hline carbonate & [tex]$CO _3^{2-}$[/tex] & ammonium & [tex]$NH _4^{+}$[/tex] \\
\hline hypocarbonite & [tex]$CO ^{2-}$[/tex] & cyanide & [tex]$CN ^{-}$[/tex] \\
\hline \begin{tabular}{l}
hydrogen carbonate \\
(bicarbonate)
\end{tabular} & [tex]$HCO _3^{-}$[/tex] & hydroxide & [tex]$OH ^{-}$[/tex] \\
\hline chlorite & [tex]$ClO _2^{-}$[/tex] & peroxide & [tex]$O _2^{2-}$[/tex] \\
\hline hypochlorite & [tex]$ClO ^{-}$[/tex] & phosphate & [tex]$PO _4^{3-}$[/tex] \\
\hline chlorate & [tex]$ClO _3^{-}$[/tex] & hydrogen phosphate & [tex]$HPO _4^{2-}$[/tex] \\
\hline
\end{tabular}

Select the correct answer.

What is the chemical formula for the compound ammonium phosphate? Use the list of polyatomic ions and the periodic table to help you answer.

A. [tex]$NH _4 H _2 PO _4$[/tex]
B. [tex]$\left( NH _4\right)_2 PO _4$[/tex]
C. [tex]$\left( NH _4\right)_3 PO _4$[/tex]
D. [tex]$\left( NH _4\right)_4 PO _4$[/tex]



Answer :

To determine the correct chemical formula for ammonium phosphate, follow these steps:

1. Identify the ions involved:
- Ammonium ion: [tex]\( NH_4^+ \)[/tex]
- Phosphate ion: [tex]\( PO_4^{3-} \)[/tex]

2. Balance the charges:
- The phosphate ion has a charge of [tex]\( 3- \)[/tex].
- The ammonium ion has a charge of [tex]\( 1+ \)[/tex].

3. Determine the number of ammonium ions needed to balance the charge of one phosphate ion:
- If each ammonium ion has a charge of [tex]\( 1+ \)[/tex], you will need three ammonium ions to balance the [tex]\( 3- \)[/tex] charge of one phosphate ion: [tex]\( 3 \times (NH_4^+) = 3+ \)[/tex]

4. Write the chemical formula:
- Combine the ions with the determined ratio from the previous step:
- The correct formula is [tex]\( (NH_4)_3PO_4 \)[/tex].

Thus, the correct chemical formula for ammonium phosphate is:

C. [tex]\( (NH_4)_3PO_4 \)[/tex]