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.

[tex]\[
\begin{tabular}{|l|l|l|l|l|}
\hline
Ion & $Na ^{+}$ & $Ca ^{2+}$ & $Fe ^{2+}$ & $Al ^{3+}$ \\
\hline
$O ^{2-}$ & $Na _2 O$ & & & \\
\hline
$NO _3^{-}$ & & & & \\
\hline
$SO _4^{2-}$ & & & & \\
\hline
$AsO _4^{3-}$ & & & & \\
\hline
\end{tabular}
\][/tex]



Answer :

Sure, I'll help you fill in the table with the formulas for the ionic compounds formed by each pair of cations and anions. Here is the detailed step-by-step solution for completing the table:

### Table Overview
We are provided with a partially completed table with the first compound already shown as [tex]\(Na_2O\)[/tex]. We need to fill in the rest of the table using the following ions:
- Cations: [tex]\(Na^+\)[/tex], [tex]\(Ca^{2+}\)[/tex], [tex]\(Fe^{2+}\)[/tex], [tex]\(Al^{3+}\)[/tex]
- Anions: [tex]\(O^{2-}\)[/tex], [tex]\(NO_3^{-}\)[/tex], [tex]\(SO_4^{2-}\)[/tex], [tex]\(AsO_4^{3-}\)[/tex]

### Step-by-Step Filling In

#### Pair 1: [tex]\(Ca^{2+}\)[/tex] and [tex]\(O^{2-}\)[/tex]
The charges are balanced directly:
- Formula: [tex]\(CaO\)[/tex]

#### Pair 2: [tex]\(Fe^{2+}\)[/tex] and [tex]\(O^{2-}\)[/tex]
The charges are balanced directly:
- Formula: [tex]\(FeO\)[/tex]

#### Pair 3: [tex]\(Al^{3+}\)[/tex] and [tex]\(O^{2-}\)[/tex]
To balance the charges, we need two [tex]\(Al^{3+}\)[/tex] ions and three [tex]\(O^{2-}\)[/tex] ions:
- Formula: [tex]\(Al_2O_3\)[/tex]

---

#### Pair 4: [tex]\(Na^+\)[/tex] and [tex]\(NO_3^{-}\)[/tex]
The charges are balanced directly:
- Formula: [tex]\(NaNO_3\)[/tex]

#### Pair 5: [tex]\(Ca^{2+}\)[/tex] and [tex]\(NO_3^{-}\)[/tex]
To balance the charges, we need one [tex]\(Ca^{2+}\)[/tex] ion and two [tex]\(NO_3^{-}\)[/tex] ions:
- Formula: [tex]\(Ca(NO_3)_2\)[/tex]

#### Pair 6: [tex]\(Fe^{2+}\)[/tex] and [tex]\(NO_3^{-}\)[/tex]
To balance the charges, we need one [tex]\(Fe^{2+}\)[/tex] ion and two [tex]\(NO_3^{-}\)[/tex] ions:
- Formula: [tex]\(Fe(NO_3)_2\)[/tex]

#### Pair 7: [tex]\(Al^{3+}\)[/tex] and [tex]\(NO_3^{-}\)[/tex]
To balance the charges, we need one [tex]\(Al^{3+}\)[/tex] ion and three [tex]\(NO_3^{-}\)[/tex] ions:
- Formula: [tex]\(Al(NO_3)_3\)[/tex]

---

#### Pair 8: [tex]\(Na^+\)[/tex] and [tex]\(SO_4^{2-}\)[/tex]
To balance the charges, we need two [tex]\(Na^+\)[/tex] ions and one [tex]\(SO_4^{2-}\)[/tex] ion:
- Formula: [tex]\(Na_2SO_4\)[/tex]

#### Pair 9: [tex]\(Ca^{2+}\)[/tex] and [tex]\(SO_4^{2-}\)[/tex]
The charges are balanced directly:
- Formula: [tex]\(CaSO_4\)[/tex]

#### Pair 10: [tex]\(Fe^{2+}\)[/tex] and [tex]\(SO_4^{2-}\)[/tex]
The charges are balanced directly:
- Formula: [tex]\(FeSO_4\)[/tex]

#### Pair 11: [tex]\(Al^{3+}\)[/tex] and [tex]\(SO_4^{2-}\)[/tex]
To balance the charges, we need two [tex]\(Al^{3+}\)[/tex] ions and three [tex]\(SO_4^{2-}\)[/tex] ions:
- Formula: [tex]\(Al_2(SO_4)_3\)[/tex]

---

#### Pair 12: [tex]\(Na^+\)[/tex] and [tex]\(AsO_4^{3-}\)[/tex]
To balance the charges, we need three [tex]\(Na^+\)[/tex] ions and one [tex]\(AsO_4^{3-}\)[/tex] ion:
- Formula: [tex]\(Na_3AsO_4\)[/tex]

#### Pair 13: [tex]\(Ca^{2+}\)[/tex] and [tex]\(AsO_4^{3-}\)[/tex]
To balance the charges, we need three [tex]\(Ca^{2+}\)[/tex] ions and two [tex]\(AsO_4^{3-}\)[/tex] ions:
- Formula: [tex]\(Ca_3(AsO_4)_2\)[/tex]

#### Pair 14: [tex]\(Fe^{2+}\)[/tex] and [tex]\(AsO_4^{3-}\)[/tex]
To balance the charges, we need three [tex]\(Fe^{2+}\)[/tex] ions and two [tex]\(AsO_4^{3-}\)[/tex] ions:
- Formula: [tex]\(Fe_3(AsO_4)_2\)[/tex]

#### Pair 15: [tex]\(Al^{3+}\)[/tex] and [tex]\(AsO_4^{3-}\)[/tex]
The charges are balanced directly:
- Formula: [tex]\(AlAsO_4\)[/tex]

---

### Completed Table

\begin{tabular}{|l|l|l|l|l|}
\hline
Ion & [tex]\(Na^+\)[/tex] & [tex]\(Ca^{2+}\)[/tex] & [tex]\(Fe^{2+}\)[/tex] & [tex]\(Al^{3+}\)[/tex] \\ \hline
[tex]\(O^{2-}\)[/tex] & [tex]\(Na_2O\)[/tex] & [tex]\(CaO\)[/tex] & [tex]\(FeO\)[/tex] & [tex]\(Al_2O_3\)[/tex] \\ \hline
[tex]\(NO_3^{-}\)[/tex] & [tex]\(NaNO_3\)[/tex] & [tex]\(Ca(NO_3)_2\)[/tex] & [tex]\(Fe(NO_3)_2\)[/tex] & [tex]\(Al(NO_3)_3\)[/tex] \\ \hline
[tex]\(SO_4^{2-}\)[/tex] & [tex]\(Na_2SO_4\)[/tex] & [tex]\(CaSO_4\)[/tex] & [tex]\(FeSO_4\)[/tex] & [tex]\(Al_2(SO_4)_3\)[/tex] \\ \hline
[tex]\(AsO_4^{3-}\)[/tex] & [tex]\(Na_3AsO_4\)[/tex] & [tex]\(Ca_3(AsO_4)_2\)[/tex] & [tex]\(Fe_3(AsO_4)_2\)[/tex] & [tex]\(AlAsO_4\)[/tex] \\ \hline
\end{tabular}