\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]$Na_2 O$[/tex] & & & \\
\hline
[tex]$NO_3^{-}$[/tex] & & & & \\
\hline
[tex]$SO_4^{2-}$[/tex] & & & & \\
\hline
[tex]$AsO_4^{3-}$[/tex] & & & & \\
\hline
\end{tabular}



Answer :

To complete the table with the missing compounds involving the given ions [tex]\((Na^+)\)[/tex], [tex]\((Ca^{2+})\)[/tex], [tex]\((Fe^{2+})\)[/tex], and [tex]\((Al^{3+})\)[/tex], we need to consider the possible compounds that can be formed with the corresponding anions [tex]\((O^{2-})\)[/tex], [tex]\((NO_3^-)\)[/tex], [tex]\((SO_4^{2-})\)[/tex], and [tex]\((AsO_4^{3-})\)[/tex].

### For [tex]\(Na^+\)[/tex]:
1. With [tex]\(O^{2-}\)[/tex]:
- Sodium oxide [tex]\((Na_2O)\)[/tex]
2. With [tex]\(NO_3^-\)[/tex]:
- Sodium nitrate [tex]\((NaNO_3)\)[/tex]
3. With [tex]\(SO_4^{2-}\)[/tex]:
- Sodium sulfate [tex]\((Na_2SO_4)\)[/tex]
4. With [tex]\(AsO_4^{3-}\)[/tex]:
- Sodium arsenate [tex]\((Na_3AsO_4)\)[/tex]

### For [tex]\(Ca^{2+}\)[/tex]:
1. With [tex]\(O^{2-}\)[/tex]:
- Calcium oxide [tex]\((CaO)\)[/tex]
2. With [tex]\(NO_3^-\)[/tex]:
- Calcium nitrate [tex]\((Ca(NO_3)_2)\)[/tex]
3. With [tex]\(SO_4^{2-}\)[/tex]:
- Calcium sulfate [tex]\((CaSO_4)\)[/tex]
4. With [tex]\(AsO_4^{3-}\)[/tex]:
- Calcium arsenate [tex]\((Ca_3(AsO_4)_2)\)[/tex]

### For [tex]\(Fe^{2+}\)[/tex]:
1. With [tex]\(O^{2-}\)[/tex]:
- Iron(II) oxide [tex]\((FeO)\)[/tex]
2. With [tex]\(NO_3^-\)[/tex]:
- Iron(II) nitrate [tex]\((Fe(NO_3)_2)\)[/tex]
3. With [tex]\(SO_4^{2-}\)[/tex]:
- Iron(II) sulfate [tex]\((FeSO_4)\)[/tex]
4. With [tex]\(AsO_4^{3-}\)[/tex]:
- Iron(II) arsenate [tex]\((Fe_3(AsO_4)_2)\)[/tex]

### For [tex]\(Al^{3+}\)[/tex]:
1. With [tex]\(O^{2-}\)[/tex]:
- Aluminum oxide (Al2O3)
2. With [tex]\(NO_3^-\)[/tex]:
- Aluminum nitrate [tex]\((Al (NO_3)_3)\)[/tex]
3. With [tex]\(SO_4^{2-}\)[/tex]:
- Aluminum sulfate [tex]\((Al_2(SO_4)_3)\)[/tex]
4. With [tex]\(AsO_4^{3-}\)[/tex]:
- Aluminum arsenate [tex]\((AlAsO_4)\)[/tex]

So, the completed table would look like this:

\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]\(Na_2 O\)[/tex] & [tex]\(CaO\)[/tex] & [tex]\(FeO\)[/tex] & [tex]\(Al_2 O_3\)[/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]\(Na_2 SO_4\)[/tex] & [tex]\(CaSO_4\)[/tex] & [tex]\(FeSO_4\)[/tex] & [tex]\(Al_2(SO_4)_3\)[/tex] \\
\hline
[tex]\(AsO_4^{3-}\)[/tex]& [tex]\(Na_3 AsO_4\)[/tex] & [tex]\(Ca_3 (AsO_4)_2\)[/tex] & [tex]\(Fe_3 (AsO_4)_2\)[/tex] & [tex]\(AlAsO_4\)[/tex] \\
\hline
\end{tabular}

Each entry in the table represents a chemically stable compound formed by combining the given cation with the specified anion.