Question

Statement I: Alkali metals dissolve in liquid ammonia to give blue solutions.
Statement II: Alkali metals in liquid ammonia give solvated species of the type $\left[M\right(N{H}_3{)}_n{]}^{\oplus }$ (M = alkali metals).
(IIT-JEE, 2007)

• A. Statement I is true; Statement II is true; Statement II is the correct explanation for Statement I.
• B. Statement I is true; Statement II is true; Statement II is not the correct explanation for Statement I.
• C. Statement I is true; Statement II is false.
• D. Statement I is false; Statement II is true.

Answer 1

The correct option is B Statement I is true; Statement II is true; Statement II is not the correct explanation for Statement I.

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

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 of electricity and have strong reducing properties. The solutions are paramagnetic in nature.