Question

answer to above question no.3

Answer 1

Balance the charges on the (positive and negative) anions and cations. Net charge must be 0.
That is the step.

Know the charge on ions and formulas first.
Potassium K+.
Sodium Na +.
Ferric Fe: +2
Calcium: Ca: +2
Aluminum: Al: +3
Sulfate: SO4 :-2
Phosphate: PO4: -3
Nitrates: NO3: -1
Hydroxide: OH: -1
Oxide: O: -2

Answers:
Na2 SO4,
KNO3 ,
Fe3 (PO4)2
Ca O.
Al (OH)3

Answer 2

Ur answer::::
Na2 SO4,
KNO3 ,
Fe3 (PO4)2
Ca O.
Al (OH)three