Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair.

Ion K+ NH+4 Mg2+ Fe3+

Cl-
OH-
CO3 2-
PO3- 4

Complete the fourth row of the table.

What would the last two be?

As you can see you can't show spaces. Is this what you mean?

K^+......NH4^+......Mg^2+ ......Fe^3+

KCl.....NH4Cl......MgCl2.......FeCl3
KOH.....NH3(aq)....Mg(OH)2.....Fe(OH)3
etc. This is how you do it. What is it you don't understand?

To determine the formula for the ionic compound formed by each pair of cations and anions, we need to balance the charges of the ions.

Looking at the pairs:

1. Cation: K+ and Anion: Cl-
The charges are balanced, so the formula is KCl.

2. Cation: NH+4 and Anion: OH-
The charges are balanced, so the formula is NH4OH.

3. Cation: Mg2+ and Anion: CO3 2-
In this case, we need two positive charges to balance the negative charge of the carbonate ion. Therefore, the formula is MgCO3.

4. Cation: Fe3+ and Anion: PO3-4
To balance the charges, we need three positive charges to balance the negative charge of the phosphate ion. Therefore, the formula is FePO4.

So, the fourth row of the table is:

Ion K+ NH+4 Mg2+ Fe3+
Cl- KCl NH4Cl MgCl2 FeCl3
OH- KOH NH4OH Mg(OH)2 Fe(OH)3
CO3 2- K2CO3 (NH4)2CO3 MgCO3 FeCO3
PO3-4 K3PO4 (NH4)3PO4 Mg3(PO4)2 FePO4

To complete the table, we need to determine the formula for the ionic compound formed by the fourth pair of cations and anions, which are Mg2+ and PO3-4.

The formula for an ionic compound can be determined by balancing the charges of the ions. The total positive charge of the cations must equal the total negative charge of the anions.

The charge of the magnesium ion (Mg2+) is 2+. The charge of the phosphate ion (PO3-4) is 4-. To balance the charges, we need two magnesium ions (2+ charge each) for every one phosphate ion (4- charge).

Therefore, the formula for the ionic compound formed by Mg2+ and PO3-4 is Mg3(PO4)2.

So, the fourth row of the table would be:
Ion: Mg2+, PO3-4
Formula: Mg3(PO4)2