Write the formula for the compound formed when the given polyatomic anion combines with a cation from the given element. Hydrogen carbonate (HCO3-) and beryllium, Nitrate (NO3-) and potassium, Sulfite (SO2/3-) and aluminum

The compound formed when the hydrogen carbonate (HCO3-) combines with beryllium is Be(HCO3)2.

The compound formed when the nitrate (NO3-) combines with potassium is KNO3.
The compound formed when the sulfite (SO2/3-) combines with aluminum is Al2(SO3)3.