An environmental chemist is handed four unlabelled flasks, each containing a different metal nitrate solution.

The metal ions present in these solutions are:

• Sodium ($N{a}^{+}$)
• Calcium ($C{a}^{2+}$)
• Iron(III) ($F{e}^{3+}$)
• Aluminium ($A{l}^{3+}$)

Describe the chemical tests the chemist should carry out to identify which metal ion is present in each flask. Include the practical procedures and all expected observations for each test.