In salt analysis cations of group I and II precipitated in acidicmedium and therefore the solution remains acidic till group II. But from III group onwards cations precipitates in basic medium and hence filtrate of group II is to be boiled with con HNO_(3) before using it for III group. The use of Br_(2) and NaOH to group III precipitate facilitates

In salt analysis cations of group I and II precipitated in acidicmediu

1.	In salt analysis cations of group I and II precipitated in acidicmedium and therefore the solution remains acidic till group II. But from III group onwards cations precipitates in basic medium and hence filtrate of group II is to be boiled with con HNO_(3) before using it for III group. The use of Br_(2) and NaOH to group III precipitate facilitates
Answer» RENDERING Al into SODIUM meta-aluminate rendering Fe into `Fe(OH)_(2)` conversion of Cr into soluble sodium chromate removal of group III ions before starting group IV Solution :`Cr^(3+)` makes soluble sodium chromate in presence of `Br_(2)//NAOH` to allow precipitation.