Question

Write formulas for the compounds that form from {\rm Rb} and each of the following polyatomic ion: {\rm NO}_{3}^{-}, {\rm SO}_{4}^{2-}, {\rm PO}_{4}^{3-}.

Answer 1

You really need to look at your posts. They don't make sense to me because of the various symbols used. Using {\rm and_ along with } is confusing unless we know what those symbols mean.
Apparently you want the formula for rubidium nitrate. RbNO3.
rubidium sulfate. Rb2SO4. We CAN write subscripts and superscripts on the board but it is too much trouble to do; therefore, we understand that Rb2SO4 means the 2 and 4 are subscripts.
rubidium phosphate is Rb3PO4.

Answer 2

Write the name of \({\rm CrPO}_{4}\)

Answer 3

ddfr

Answer 4

hell no