In qualitative test for identification of presence of phosphorous, the compound is heated with an oxidising agent. Which is further treated with nitric acid and ammonium molybdate respectively. The yellow coloured precipitate obtained is :
(1) \(Na_3 PO _4.12 MoO_3\)
(2) \((NH_4)_3 PO_4 .12 (NH_4)_2 MoO_4\)
(3) \((NH_4) _3 PO_4 .12 MoO_3\)
(4) \(MoPO_4 .21 NH_4 NO_3\)