The most soluble of the compounds given above is [NH4]3PO4. [NH4]3PO4 is a salt of ammonium and phosphate; it is a white crystal at room temprature. It is an highly unstable compound and thus easily decompose when mixed with water.
Multiply,
moles * molar mass = mass
Pka = - log ka
10.36 = - log ka
Ka = .......
Because their atoms have the same number of electrons in the highest occupied energy level
