Phosphates give canary yellow precipitate with ammonium molybdate in the presence of conc. HNO 3
\begin{array}{l}
H _{3} PO _{4}+12\left( NH _{4}\right)_{2} MoO _{4}+21 HNO _{3} \\
\rightarrow\left( NH _{4}\right)_{3} PO _{4} \cdot 12 MoO _{3}+21 NH _{4} NO _{3}+12 H _{2} O
\end{array}
ammonium phosphomolybdate (canary yellow ppt.)