Why does ammonium belong to group zero?

Answer 1

NH4+ is kept in group zero of qualitative analysis because it is the only non metallic
cation. . its test is quite different than that of other cations.
it does not resemble any other cation so it tested first of all in zero group .
the reagent for zero group is Na OH solution.
if it is not tested in zero group then in the subsequent groups we use NH4 OH as
reagents. then the solution will automatically contains NH4+ ion if it would have
not been present in the original mixture to analysed.
SO IT IS EVIDENT THAT THE NH4+SHOULD BE KEPT IN ZERO GROUP.

Answer 2

Ammonium is a positively charged polyatomic ion (NH4+) derived from ammonia (NH3) combining with a proton (H+). It is named ammonium and not ammonia because it has gained a proton, giving it a positive charge. In the context of group zero, it may be considered a cation with a charge of +1.