Question

Highly pure dilute solution of sodium in liquid ammonia
(IIT-JEE, 1998)

• A. Shows blue colour
• B. Exhibits electrical conductivity
• C. Produces sodium anide
• D. Produces hydrogen gas

Answer 1

Answer: (A), (B)

The correct options are
A Shows blue colour
B Exhibits electrical conductivity

The alkali metals dissolve in liquid ammonia without the evolution of hydrogen. The colour of the dilute solution is blue.
$N{a}^{\oplus }+(x+y)N{H}_2\to \left[Na\right(N{H}_3{)}_x{]}^{\oplus }+\left[e\right(N{H}_3{)}_y{]}^{\ominus }$
Ammonia
electrons

On heating, its blue colour changes to bronze.

It is an ammoniated electron which is responsible for the colour and other properties. The solutions are good conductors fo electricity and have strong reducing properties. The solutions are paramagnetic in nature.