c
\(\underset{\text{Acidic}}{\mathop{{{P}_{4}}{{O}_{10}}}}\,\,+\,2{{H}_{2}}O\,\to \underset{\begin{smallmatrix}
\text{meta phosphoric} \\
\text{ acid}
\end{smallmatrix}}{\mathop{\,4HP{{O}_{3}}\,}}\,\xrightarrow[basic]{N{{H}_{3}}}\underset{\begin{smallmatrix}
\text{meta ammonium} \\
\text{ phosphate}
\end{smallmatrix}}{\mathop{N{{H}_{4}}P{{o}_{3}}}}\,\)