Write the formulas for the following compounds: (a) rubidium nitrite, (b) potassium sulfide, (c) sodium hydrogen sulfide, (d) magnesium phosphate, (e) calcium hydrogen phosphate, (f) potassium dihydrogen phosphate, (g) iodine heptafluoride, (h) ammonium sulfate, (i) silver perchlorate, (j) boron trichloride.

Rubidium (Rb) is a group I element and hence has a +1 charge. Nitrite is a polyatomic ion with a formula NO2- and charge of -1. Potassium (K) is also a group I element with a +1 charge. Sulfide ion (S) has a -2 charge. Sodium (Na) has a +1 charge, hydrogen sulfide is HS-, phosphate is PO4 with -3 charge, calcium (Ca) has a +2 charge, hydrogen phosphate is HPO4 with -2 charge, iodine (I) has -1 charge, while fluoride ion (F) has -1 charge, hepta signifies 7 fluoride ions are present. Ammonium ion is NH4+ and sulfate is SO4 with -2 charge. Silver (Ag) has a +1 charge and perchlorate is ClO4 with -1 charge. Lastly, boron (B) has +3 charge and chloride ion (Cl) has -1 charge.

In Rubidium nitrite, Rb has +1 charge and NO2 has -1 charge, by balancing the charge, the chemical formula will be RbNO2. In potassium sulfide, K has +1 charge and S has -2 charge, the balanced formula will be K2S. For sodium hydrogen sulfide, Sodium has +1 charge and HS has -1 charge, hence the chemical formula will be NaHS. In magnesium phosphate, magnesium (Mg) has +2 charge whereas phosphate has -3 charge, hence the balanced chemical formula will be Mg3(PO4)2. For calcium hydrogen phosphate, calcium has +2 charge and HPO4 has -2 charge, making the chemical formula CaHPO4. For potassium dihydrogen phosphate, potassium has +1 charge whereas H2PO4 ion (dihydrogen phosphate) has -1 charge, hence the balanced chemical formula will be KH2PO4. For iodine heptafluoride, iodine has +7 charge and fluoride has -1 charge, making the balanced chemical formula IF7. Ammonium sulfate will be (NH4)2SO4 because ammonium has +1 charge and sulfate has -2 charge. For silver perchlorate, silver has +1 charge and perchlorate has -1 charge, hence the chemical formula will be AgClO4. Boron trichloride will be BCl3 because boron has +3 charge and chloride has -1 charge.