To determine the formulas of compounds formed by NH4+ with the given anions, we can simply combine the charges to achieve a neutral compound.
1. NH4+ with NO3−:
The compound formed is ammonium nitrate.
NH4+ + NO3− = NH4NO3
2. NH4+ with HCO3−:
The compound formed is ammonium bicarbonate.
NH4+ + HCO3− = NH4HCO3
3. NH4+ with SO42−:
The compound formed is ammonium sulfate.
NH4+ + SO42− = (NH4)2SO4
4. NH4+ with HPO42−:
The compound formed is ammonium hydrogen phosphate.
NH4+ + HPO42− = NH4HPO4
So, the formulas of the compounds formed are NH4NO3, NH4HCO3, (NH4)2SO4, and NH4HPO4, respectively.