Explanation:

Alkali metals such as lithium (Li), sodium (Na), and potassium (K) are highly reactive metals that readily react with various substances including ammonia (NH3). When alkali metals dissolve in liquid ammonia, they form a blue solution. This blue color is due to the formation of ammoniated electrons.

Formation of Ammoniated Electrons:
- When an alkali metal (M) dissolves in liquid ammonia (NH3), the metal atoms lose their outermost valence electron(s) to form metal cations (M+).
- These metal cations (M+) are then surrounded by ammonia molecules (NH3) which act as ligands.
- The ammonia molecules coordinate with the metal cations, donating their lone pair of electrons to the metal cations.
- As a result, the metal cations become ammoniated metal cations (M(NH3)n)+, where n represents the coordination number or the number of ammonia molecules coordinated to the metal cation.
- The coordination of ammonia molecules stabilizes the metal cations in solution.

Blue Color:
- The blue color of the solution is due to the presence of ammoniated electrons.
- When the metal cations coordinate with ammonia molecules, some of the electrons from the ammonia molecules become delocalized and form a cloud of ammoniated electrons around the metal cations.
- These delocalized ammoniated electrons absorb light in the visible region of the electromagnetic spectrum, particularly in the blue region, and give rise to the blue color of the solution.

Summary:
- Alkali metals dissolve in liquid ammonia to form ammoniated metal cations.
- The coordination of ammonia molecules stabilizes the metal cations in solution.
- The blue color of the solution is due to the presence of ammoniated electrons, which absorb light in the blue region of the electromagnetic spectrum.