Express your answer as a chemical formula.

1.Cr^-3 and Br^-

2. Fe^3+ and O^2-

3.Hg2^2+ and CO3^2-

4.Ca^2+ and CIO^3-

5. NH^+4 and PO4^3-

CrBr3

Hg2CO3

(NH4)3 PO4

CrBr3

Fe2O3

Hg2CO3

Ca3ClO2

(NH4)3PO4

1. Cr^-3 and Br^- - CrBr3

2. Fe^3+ and O^2- - Fe2O3
3. Hg2^2+ and CO3^2- - Hg2(CO3)2
4. Ca^2+ and CIO^3- - Ca(CIO3)2
5. NH^+4 and PO4^3- - (NH4)3PO4

To express the chemical formulas for these combinations of ions, you need to write the symbol for the cation (positive ion) followed by the symbol for the anion (negative ion). Make sure to balance the charges to create a neutral compound, if necessary. Here are the chemical formulas for each combination you provided:

1. Cr^3- and Br^-: CrBr3
To obtain this formula, you need to have three bromide ions to balance the charge of a single chromium ion.

2. Fe^3+ and O^2-: Fe2O3
To balance the charges, you need two iron(III) ions (Fe^3+) to balance the charge of three oxide ions (O^2-).

3. Hg2^2+ and CO3^2-: Hg2(CO3)2
To balance the charges, you need two mercury(I) ions (Hg2^2+) to balance the charge of one carbonate ion (CO3^2-). The parentheses are used to indicate that the carbonate ion is a polyatomic ion.

4. Ca^2+ and ClO3^-: Ca(ClO3)2
To balance the charges, you need two calcium ions (Ca^2+) to balance the charge of one chlorate ion (ClO3^-). Again, parentheses are used to indicate that the chlorate ion is a polyatomic ion.

5. NH4^+ and PO4^3-: (NH4)3PO4
To balance the charges, you need three ammonium ions (NH4^+) to balance the charge of one phosphate ion (PO4^3-). The parentheses are used to indicate that the ammonium ion is a polyatomic ion, and the subscript outside the parentheses indicates the number of ammonium ions present in the compound.